c.md

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C

CA : → Certificate Authority : → Confidentiality Agreement

Cache : A hardware or software component that stores data so that future requests for that data can be served faster. The data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store. †

Cache busting : A type of HTTP flood attack that uses query variations to get around caching. Instead of returning results from the cache, other servers must be contacted which increases their load to potentially overwhelm them.

Cache eviction : The automatically or manually requested removal of old, unused, or large data from a cache.

Cache partitioning : The dividing and assigning of cache space to different system or application tasks, in order to improve security (as with browser cache partitioning) or performance.

Cache poisoning : → DNS spoofing

California Consumer Privacy Act : A state statute intended to enhance privacy rights and consumer protection for residents of California, United States. The bill was passed in 2018, amending the California Civil Code. The intentions of the CCPA are to provide California residents with the right to know what personal data is being collected about them; to know whether their personal data is sold or disclosed and to whom; to say no to the sale of personal data; to access their personal data; to request a business to delete personal information about a consumer collected from that consumer; and not to be discriminated against for exercising their privacy rights. †

Call stack : A mechanism for an interpreter (like the JavaScript interpreter in a web browser) to keep track of its place in a script that calls multiple functions—what function is currently being run and what functions are called from within that function, etc. ‡

Call to Action : A marketing term used extensively in advertising and selling. It refers to any device designed to prompt an immediate response or encourage an immediate sale. A CTA most often refers to the use of words or phrases that can be incorporated into sales scripts, advertising messages or web pages that encourage consumers to take prompt action. †

Callback : Executable code that is provided as an argument to other code that executes—calls back—that argument immediately (synchronous callback) or at a later time (asynchronous callback). †

Callback queue : A queue of messages (functions) that are processed in a “first in, first out” order (FIFO) by the JavaScript event loop.

Camel case : The practice of writing phrases such that each word or abbreviation in the middle of the phrase begins with a capital letter, with no intervening spaces or punctuation. Common examples include “iPhone” and “eBay.” Camel case is also sometimes used in online usernames such as “johnSmith.” In programming, camel case is often used for variable names. †

Camino : A discontinued GUI-based web browser based on Mozilla’s Gecko layout engine, specifically designed for the OS X operating system. In place of an XUL-based user interface used by most Mozilla-based applications, Camino used Mac-native Cocoa APIs. In 2013, the Camino Project stopped the development of the browser. †

Canary : Software that is only released to a small group of users, making it easy to roll it back in case of serious defects. The name comes from canaries that were once used in coal mines to warn of dangerous levels of carbon monoxide.

Candidate Recommendation : The specification-testing phase of a World Wide Web Consortium (W3C) specification (also known as a recommendation).

Canonical equivalence : The assuming of code point sequences to have the same appearance and meaning when printed or displayed. †

Canonical link : An HTML element marked rel=canonical that helps webmasters prevent duplicate content issues in search engine optimization by specifying the “canonical” or “preferred” version of a web page. †

Canonical Name : A type of resource record in the Domain Name System (DNS) which maps one domain name (an alias) to another (the canonical name). †

Canvas : A container, the HTML canvas element, that allows for dynamic, scriptable rendering of 2D and 3D shapes and bitmap images by providing an empty graphic zone on which specific JavaScript APIs can draw (such as Canvas 2D or WebGL). ‡

CAP Theorem : A theoretical computer science theorem that states that it is impossible for a distributed data store to simultaneously provide more than two out of the following three guarantees: 1) Consistency: Every read receives the most recent write or an error. 2) Availability: Every request receives a (non-error) response, without the guarantee that it contains the most recent write. 3) Partition tolerance: The system continues to operate despite an arbitrary number of messages being dropped (or delayed) by the network between nodes. The CAP Theorem implies that in the presence of a network partition, one has to choose between consistency and availability. †

CAPTCHA : A type of challenge-response test used in computing to determine whether the user is human. The term stands for “completely automated public Turing test to tell computers and humans apart” and was coined in 2003 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford. †

Card sorting : A method that aids the design or evaluation of the information architecture of a website. Card sorting is usually performed with groups, with attendees organizing topics into categories or folksonomies.

Caret : A grapheme—“^”, “‸”, “⁁”, or “＾”—with several uses, including as a proofreading mark, as a special character in programming languages, as an escape character, or for estimation. †

Carousel : A slideshow-like design element for web pages. A carousel allows focus on one unit of content and media while providing access to similar units (by some way of carousel navigation).

Cascade : The order by which declarations are applied in CSS: 1) per target media type; 2) per importance and origin (from user agent to important user declarations); 3) by specificity; and 4) by order in which the declaration was specified (with all having the same weight, origin, and specificity, the latest declaration prevails).

Cascading HTML Style Sheets : A style sheet language proposal drafted in 1994 by Håkon Wium Lie. ℹ︎ w3.org/People/howcome/p/cascade

Cascading Style Sheets : A style sheet language that allows to manage the presentation of markup languages like HTML or XML. The first final specification of CSS was published in 1996 by Håkon Wium Lie and Bert Bos. ℹ︎ w3.org/Style/CSS

Case : In engineering, as use case, a list of actions or event steps typically defining the interactions between a role (known in UML as an actor) and a system to achieve a goal. The actor can be a human or other external system. In systems engineering, use cases are used at a higher level than within software engineering, often representing missions or stakeholder goals. † : In programming, a selection mechanism to allow a variable to change the flow of a program. † : In typography, as letter case, the distinction between the letters that are in larger upper case (also uppercase, capital letters, capitals, caps, large letters, or more formally majuscule) and smaller lower case (also lowercase, small letters, or more formally minuscule) in the written representation of certain languages. †

catch : → try…catch

CBD : → Component-Based Development

CBSE : → Component-Based Software Engineering

CC/PP : → Composite Capability/Preference Profiles

CCPA : → California Consumer Privacy Act

CCT : → Chrome Custom Tabs

ccTLD : → Country code top-level domain

CD : → Corporate Design : → Continuous Delivery : → Continuous Deployment

CDATA : → Character Data

CDN : → Content Delivery Network

CDP : → Chrome DevTools Protocol

CERT : A certificate resource record in the Domain Name System (DNS). †

Certificate : An electronic document used to prove the ownership of a public key. The certificate includes information about the key, information about the identity of its owner (called the subject), and the digital signature of an entity that has verified the certificate’s contents (called the issuer). †

Certificate Authority : An entity that issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate. This allows others to rely upon signatures or on assertions made about the private key that corresponds to the certified public key. A CA acts as a trusted third party, trusted both by the subject (owner) of the certificate and by the party relying upon the certificate. The format of these certificates is specified by the X.509 standard. One particularly common use for certificate authorities is to sign certificates used in HTTPS, the secure browsing protocol for the World Wide Web. †

CES : → Customer Effort Score

CFML : → ColdFusion Markup Language

CGI : → Common Gateway Interface

Chaining : The calling of several methods after another on an object.

Change list : The set of changes made in a single commit. This can also represent a sequential view of the source code, allowing the examination of source as of any particular changelist ID. †

Change set : → Change list

Changeset : A method to handle multi-package changes and versions. ℹ︎ github.com/atlassian/changesets

Channel messaging : An API described by the HTML specification that enables independent pieces of code (e.g., scripts in different browsing contexts) to communicate directly. Channel messaging works through two-way channels (or pipes) with a port at each end. ‡

Chaos engineering : The discipline of experimenting on a software system in production in order to build confidence in the system’s capability to withstand turbulent and unexpected conditions. Chaos engineering can be used to achieve resilience against infrastructure, network, and application failures. †

Character : An encoded symbol that maps to a glyph.

Character Data : A concept used for distinct but related purposes in the markup languages SGML and XML. “CDATA” indicates that a certain portion of the document is general character data, rather than non-character data or character data with a more specific, limited structure. †

Character encoding : A mapping of code points to characters, like UTF-8.

Character entity reference : A character reference that refers to a character by the name of an entity which has the desired character as its replacement text. The entity must either be predefined (built into the markup language) or explicitly declared in a document type definition (DTD). The format is the same as for any entity reference: &name;, where “name” is the case-sensitive name of the entity. †

Character reference : → Character entity reference : → Numeric character reference

Character set : → Character encoding

Charset : → Character encoding

CheiRank : An eigenvector with a maximal real eigenvalue of the Google matrix G^*^ constructed for a directed network with the inverted directions of links. CheiRank is similar to the PageRank vector, which ranks the network nodes in average proportionally to a number of incoming links being the maximal eigenvector of the Google matrix G with a given initial direction of links. Due to inversion of link directions the CheiRank ranks the network nodes in average proportionally to a number of outgoing links. †

Chrome : A cross-platform web browser, based on the Chromium browser project. Chrome was released in 2008 by Google. ℹ︎ google.com/chrome : The graphical elements of a web browser, like title, address, and status bar as well as navigation elements.

Chrome Custom Tabs : A Chrome feature that allows native apps to invoke the Chrome browser with customized actions, toolbars, and animations.

Chrome DevTools : A set of web developer tools built directly into the Chrome web browser. ℹ︎ is.gd/TsOXbb

Chrome DevTools Protocol : A protocol to “instrument, inspect, debug, and profile” Chromium, Chrome, and other Blink-based browsers. ℹ︎ is.gd/a55qQ3

Chrome OS : A Linux kernel-based operating system designed by Google. Chrome OS is derived from the free software Chromium OS and uses the Google Chrome web browser as its principal user interface. Google announced Chrome OS in 2009, conceiving it as an operating system in which both applications and user data reside in the cloud—hence Chrome OS primarily runs web applications. Chrome OS is only available pre-installed on hardware from Google manufacturing partners, but there are unofficial methods that allow it to be installed in other equipment. † ℹ︎ google.com/chromebook/chrome-os

ChromeVox : A screen reader for Chrome OS as well as the Chrome web browser developed by Google. ℹ︎ chromevox.com

Chromium : A Google-developed project whose source code can be compiled into a web browser. Google’s Chrome browser is based on the Chromium code, as are several other browsers, including Edge, Opera, and Silk. Other parties have compiled the code as-is, releasing their browsers under the Chromium name. † ℹ︎ chromium.org

CHSS : → Cascading HTML Style Sheets

CI : → Continuous Integration : → Corporate Identity

CIDR : → Classless Inter-Domain Routing

Cipher : An algorithm for encryption or decryption. To encipher or encode is to convert information into cipher or code. †

CircleCI : A continuous integration and delivery platform. CircleCI was founded in 2011. ℹ︎ circleci.com

CL : → Change list

Class : An extensible program code template for creating objects, providing initial values for state (member variables), and implementations of behavior (member functions or methods). In many languages, the class name is used as the name for the class (the template itself), the name for the default constructor of the class (a subroutine that creates objects), and as the type of objects generated by instantiating the class. † : In web development, the (value of the) class attribute, usually used as a selector for styling purposes.

Class variable : Any variable declared with the static modifier of which a single copy exists, regardless of how many instances of the class there are. †

Classitis : In software development, a negative outcome of the disputed goal to work with many small classes. : In web development, the excessive use of class attributes and values.

Classless Inter-Domain Routing : A method for allocating IP addresses and for IP routing. The Internet Engineering Task Force (IETF) introduced CIDR in 1993 to replace the previous classful network addressing architecture on the Internet. The goal of CIDR was to slow the growth of routing tables on routers across the Internet, and to help slow the rapid exhaustion of IPv4 addresses. †

Clearfix : A name for a variety of float-clearing techniques that may (when CSS-only) or may not (as with relying on presentational helper classes) meet development best practices. ℹ︎ is.gd/ywDpA3

CLI : → Command-Line Interface

Click : A physical or emulated interaction with a pointing device.

Click-through rate : The ratio of users who click on a specific link to the number of total users who view a page, email, or advertisement. It is commonly used to measure the success of an online advertising campaign for a particular website as well as the effectiveness of email campaigns. †

Clickjacking : A malicious technique of tricking a user into clicking on something different from what the user perceives, thus potentially revealing confidential information or allowing others to take control of the user’s computer. †

Client : A piece of computer hardware or software that accesses a service made available by a server. The server is often (but not always) on another computer system, in which case the client accesses the service by way of a network. †

Client Hints : A set of HTTP request header fields for proactive content negotiation allowing clients to indicate a list of device and agent specific preferences. Client Hints enable automated delivery of optimized assets, like the automatic negotiation of image DPR resolution. ‡ ℹ︎ is.gd/NIdm5F

Client side : Operations on the client as opposed to the server side in a client-server relationship. †

Client-Side Rendering : A technique in which a page is rendered on the client side, as opposed to the server side (as with SSR). On the first request, only a skeleton (a minimal HTML document) is returned by the server. It is then populated on the client side, usually via JavaScript, to turn it into a fully rendered page.

Cloaking : A search engine optimization (SEO) technique in which the content presented to the search engine spider is different from that presented to a user’s browser. This can be done by delivering content based on the IP addresses or the User-Agent HTTP header of the user requesting the page. When a user is identified as a search engine spider, a server-side script delivers a different version of the web page, one that contains content not present on the visible page, or that is present but not searchable. The purpose of cloaking is to deceive search engines so they display the page when it would not otherwise be displayed (black hat SEO). However, it can also be a functional (though antiquated) technique for informing search engines of content they would not otherwise be able to locate. †

Clojure : A dynamic and functional dialect of the Lisp programming language on the Java platform. Like other Lisp dialects, Clojure treats code as data and has a Lisp macro system. The development process is community-driven, overseen by Rich Hickey as a “benevolent dictator for life” (BDFL). Clojure advocates immutability and immutable data structures and encourages programmers to be explicit about managing identity and its states. † ℹ︎ clojure.org

Clone detection : The automated process of finding duplication in source code. †

Closure : A technique for implementing lexically scoped name binding in a language with first-class functions. Operationally, a closure is a record storing a function together with an environment. The environment is a mapping associating each free variable of the function (variables that are used locally, but defined in an enclosing scope) with the value or reference to which the name was bound when the closure was created. Unlike a plain function, a closure allows the function to access those captured variables through the closure’s copies of their values or references, even when the function is invoked outside their scope. †

Cloud : → Cloud computing : → Cloud storage

Cloud computing : The on-demand availability of computer system resources, especially data storage and computing power, without direct active management by the user. The term is generally used to describe data centers available to many users over the Internet. Large clouds, predominant today, often have functions distributed over multiple locations from central servers. If the connection to the user is relatively close, it may be designated an edge server. †

Cloud storage : A model of computer data storage in which the digital data is stored in logical pools. The physical storage spans multiple servers (sometimes in multiple locations), and the physical environment is typically owned and managed by a hosting company. These cloud storage providers are responsible for keeping the data available and accessible, and the physical environment protected and running. †

CLS : → Cumulative Layout Shift

Cluster : A set of loosely or tightly connected computers that work together so that, in many respects, they can be viewed as a single system. Unlike grid computers, computer clusters have each node set to perform the same task, controlled and scheduled by software. †

CMP : → Consent Management Platform

CMS : → Content Management System

CMYK : → Cyan, Magenta, Yellow, and Key

CNAME : → Canonical Name

CNAME cloaking : The disguising of third-party resources as first-party resources through the modification of domain CNAME entries. CNAME cloaking is used to get around tracking protections.

Coalescing : The merging of two adjacent free blocks of memory, which is relevant as when an application frees memory, gaps can fall in the memory segment that the application uses. † : A way to provide a default value if an operand is null or undefined. This so-called null or nullish coalescing allows a default value to be defined for cases where a more specific value is not available. †

CoC : → Code of Conduct : → Convention over Configuration

Code : The set of instructions forming a computer program which is executed by a computer. It is one of two components of the software which runs on computer hardware, the other being the data. †

Code coverage : A measure used to describe the degree to which the source code of a program is executed when a particular test suite runs. A program with high test coverage, measured as a percentage, has had more of its source code executed during testing, which suggests it has a lower chance of containing undetected software bugs compared to a program with low test coverage. Many different metrics can be used to calculate test coverage; some of the most basic are the percentage of program subroutines and the percentage of program statements called during execution of the test suite. †

Code debt : → Technical debt

Code golf : A type of recreational computer programming competition in which participants strive to achieve the shortest possible source code that implements a certain algorithm. Playing code golf is known as “golf scripting.” Code golf tournaments may also be named with the programming language used (for example, Perl golf). †

Code of Conduct : A set of rules outlining the norms, rules, and responsibilities of, or proper practices for, an individual. †

Code point : Any of the numerical values that make up the code space for a character encoding. Many code points represent single characters but they can also have other meanings, such as for formatting. †

Code refactoring : → Refactoring

Code review : A software quality assurance activity in which one or several people check a program mainly by viewing and reading parts of its source code, and they do so after implementation or as an interruption of implementation. At least one of the persons must not be the code’s author. The persons performing the checking, excluding the author, are called reviewers. †

Code smell : Any characteristic in the source code of a program that possibly indicates a deeper problem. Determining what is and is not a code smell is subjective, and varies by language, development methodology, and developer. The term “code smell” was popularized in the late 1990s by Kent Beck. †

Code splitting : The splitting of code into various bundles or components which can then be loaded on demand or in parallel. While the total amount of code is the same (and perhaps even a little larger), the amount of code needed during initial load can be reduced. ‡

Codeline : → Branch

CodePen : An online community for testing and showcasing user-created HTML, CSS, and JavaScript code snippets. It functions as a code editor and learning environment, where developers can create code snippets, called pens, test, and share them. CodePen was founded in 2012. † ℹ︎ codepen.io

Coding by Convention : → Convention over Configuration

Coding guidelines : Rules for how code is to be designed and formatted. Coding guidelines are usually established in organizations with several developers and development teams.

COEP : → Cross-Origin-Embedder-Policy

CoffeeScript : A programming language that compiles to JavaScript. It adds syntactic sugar inspired by Ruby, Python, and Haskell in an effort to enhance JavaScript’s brevity and readability. Specific additional features include list comprehension and destructuring assignment. † ℹ︎ coffeescript.org

Cognitive disability : As disabilities affecting cognitive ability, a concept encompassing various intellectual or cognitive deficits, including intellectual disability (formerly called mental retardation), deficits too mild to properly qualify as intellectual disability, various specific conditions (such as specific learning disability), and problems acquired later in life through acquired brain injuries or neurodegenerative diseases like dementia. Many of these disabilities have an effect on memory, which is the ability to recall what has been learned over time. †

Cold data : Rarely accessed data.

ColdFusion : A commercial rapid web application development computing platform created in 1995 by J.J. Allaire. (The programming language used with the platform is also commonly called ColdFusion, though is more accurately known as CFML.) ColdFusion was originally designed to make it easier to connect simple HTML pages to a database. By version 2 (1996), it became a full platform that included an IDE in addition to a full scripting language. † ℹ︎ is.gd/r6E53v

ColdFusion Markup Language : A scripting language for web development that runs on the Java virtual machine, the .NET framework, and Google App Engine. Multiple implementations of CFML engines are available, including Adobe ColdFusion, Lucee, New Atlanta BlueDragon, Railo, and Open BlueDragon. †

Collapsed margin : → Margin collapsing

Color blindness : The decreased ability to see color or differences in color. 8% of men and 0.5% of women have some form of color blindness. The most common forms of color blindness are deuteranomaly, deuteranopia, protanomaly, and protanopia. †

Color circle : → Color wheel

Color management : The controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset presses, and corresponding media. The primary goal of color management is to obtain a good match across color devices; for example, the colors of one frame of a video should appear the same on a computer LCD monitor, on a plasma TV screen, and as a printed poster. Color management helps to achieve the same appearance on all of these devices, provided the devices are capable of delivering the needed color intensities. Color management cannot guarantee identical color reproduction, as this is rarely possible, but it can at least give more control over any changes which may occur. †

Color scheme : The choice of colors used in design to create style and appeal. Colors that create an aesthetic feeling when used together will commonly accompany each other in color schemes. †

Color wheel : An abstract illustrative organization of color hues around a circle, which shows the relationships between primary colors, secondary colors, tertiary colors, etc. Some sources use the terms “color wheel” and “color circle” interchangeably; however, one term or the other may be more prevalent in certain fields. †

Comma-Separated Values : As a CSV file, a delimited text file that uses a comma to separate values. Each line of the file is a data record. Each record consists of one or more fields, separated by commas. The use of the comma as a field separator is the source of the name for this file format. A CSV file typically stores tabular data (numbers and text) in plain-text, in which case each line will have the same number of fields. The CSV file format is not fully standardized. †

Command : A directive to a computer program to perform a specific task. It may be issued via a command-line interface, such as a shell, or as input to a network service as part of a network protocol, or as an event in a graphical user interface triggered by the user selecting an option in a menu. †

Command-Line Interface : An interface processing commands to a computer program in the form of lines of text. Operating systems implement command-line interfaces in a shell for interactive access to operating system functions or services. †

Command-Query Separation : A principle of imperative computer programming. CQS was devised by Bertrand Meyer as part of his pioneering work on the Eiffel programming language. The principle states that every method should either be a command that performs an action, or a query that returns data to the caller, but not both. In other words, “Asking a question should not change the answer.” More formally, methods should return a value only if they are referentially transparent and hence possess no side effects. †

Comment : A developer-readable explanation or annotation in the source code of a computer program. Comments are added with the purpose of making the source code easier for humans to understand, and are generally ignored by compilers and interpreters. The syntax of comments in various programming languages varies considerably. †

Common Gateway Interface : An interface specification for web servers to execute programs that execute like console applications (also called command-line interface programs) running on a server that generates web pages dynamically. Such programs are known as CGI scripts, or simply as CGIs. The specifics of how the script is executed by the server are determined by the server. In the common case, a CGI script executes at the time a request is made and generates HTML. †

Common Vulnerabilities and Exposures : A system that provides a reference method for publicly known information security vulnerabilities and exposures. The United States’ National Cybersecurity FFRDC, operated by The Mitre Corporation, maintains the system, with funding from the U.S. National Cyber Security Division of the U.S. Department of Homeland Security. The CVE system was officially launched for the public in 1999. † ℹ︎ cve.mitre.org

Common Vulnerability Scoring System : An industry standard for assessing the severity of computer system security vulnerabilities. CVSS assigns severity scores to vulnerabilities, allowing responders to prioritize responses and resources according to threat. Scores are calculated based on a formula that depends on several metrics that approximate the ease and impact of an exploit. Scores range from 0 to 10, with 10 being the most severe. CVSS version 1 (CVSSv1) was released in 2005. † ℹ︎ first.org/cvss

CommonJS : A discontinued project with the goal to establish conventions on a module ecosystem for JavaScript outside of the web browser. The primary reason for its creation was a major lack of commonly accepted form of JavaScript scripts module units which could be reusable in environments different from that provided by a conventional web browser. CommonJS maintains specifications (including drafts) and a list of implementations. Work on CommonJS started in 2009, and ended in 2014. †

CommonMark : A plain-text format compatible with Markdown. CommonMark was started as a standardization effort in 2012. ℹ︎ commonmark.org

Community of Practice : A group of people who share a craft or a profession. The concept was first proposed in 1991 by Jean Lave and Etienne Wenger. A CoP can evolve naturally because of the members’ common interest in a particular domain or area, or it can be created deliberately with the goal of gaining knowledge related to a specific field. It is through the process of sharing information and experiences with the group that members learn from each other, and have an opportunity to develop personally and professionally. CoPs can exist in physical settings, for example, a lunchroom at work, a field setting, a factory floor, or elsewhere in the environment, but members of CoPs do not have to be co-located. †

Compared to what? : A question data graphics must be able to answer, according to distinguished information design expert Erward Tufte.

Compass : A CSS authoring framework. ℹ︎ compass-style.org

Compatibility : The ability of software to run on a particular architecture or operating system, and the ability of hardware to work with a particular CPU architecture, bus, motherboard, or operating system. Compatible software and hardware may not always run at its highest stated performance. †

Compatibility equivalence : The assuming of code point sequences to have possibly distinct appearances, but the same meaning in some contexts. †

Compatibility mode : A software mechanism in which a software either emulates an older version of software, or mimics another operating system in order to allow older or incompatible software or files to remain compatible with the computer’s newer hardware or software. Examples of software using this mode are operating systems and Internet Explorer. †

Compiler : A computer program that translates computer code written in one programming language (the source language) into another language (the target language). The name “compiler” is primarily used for programs that translate source code from a high-level programming language to a lower level language (e.g., assembly language, object code, or machine code) to create an executable program. †

Compiling : The translating of computer code written in one programming language into another language. †

Complementary colors : Pairs of colors which, when combined or mixed, cancel each other out (lose hue) by producing a grayscale color like white or black. When placed next to each other, they create the strongest contrast for those two colors. Complementary colors may also be called opposite colors. Modern color theory uses either the RGB additive color model or the CMY subtractive color model, and in these, the complementary pairs are red-cyan, green-magenta, and blue-yellow. In the traditional RYB color model, the complementary color pairs are red-green, yellow-purple, and blue-orange. Opponent process theory suggests that the most contrasting color pairs are red-green and blue-yellow. †

Component : A software package, a web service, a web resource, or a module that encapsulates a set of related functions or data. All system processes are placed into separate components so that all of the data and functions inside each component are semantically related (just as with the contents of classes). Because of this principle, it is often said that components are modular and cohesive. †

Component library : → Pattern library

Component-Based Development : → Component-Based Software Engineering

Component-Based Software Engineering : A branch of software engineering that emphasizes the separation of concerns with respect to the wide-ranging functionality available throughout a given software system. It is a reuse-based approach to defining, implementing, and composing loosely coupled independent components into systems. †

Composite Capability/Preference Profiles : A specification for defining capabilities and preferences of user agents, establishing a delivery context that can be used to guide the process of tailoring content. CC/PP is a vocabulary extension of the Resource Description Framework (RDF). † ℹ︎ w3.org/TR/CCPP-struct-vocab2

Compression : The process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. †

Computer programming : → Programming

Concurrency : The ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the final outcome. This allows for parallel execution of the concurrent units, which can significantly improve overall speed of the execution in multi-processor and multi-core systems. †

Concurrent Versioning System : → Concurrent Versions System

Concurrent Versions System : A client-server version control system. CVS was developed in 1986 by Dick Grune. † ℹ︎ savannah.nongnu.org/projects/cvs

Conditional : A feature of a programming language which perform different computations or actions depending on whether a programmer-specified Boolean condition evaluates to true or false. Apart from the case of branch predication, this is achieved by selectively altering the control flow based on some condition. In imperative programming languages, the term “conditional statement” is usually used, whereas in functional programming, “conditional expression” or “conditional construct” are preferred. †

Conditional Comments : Conditional statements in HTML, interpreted by Microsoft Internet Explorer 5–9. Conditional comments can be used to provide and hide code to and from Internet Explorer. Conditional comments are no longer supported in Internet Explorer 10 and 11. †

Cone of Uncertainty : A model for the evolution of the amount of best case uncertainty during a project. At the beginning of a project, comparatively little is known about the product or work results, and so estimates are subject to large uncertainty. As more research and development is done, more information is learned about the project, and the uncertainty then tends to decrease. The change in uncertainty makes for the shape of a cone. †

Confidence testing : → Smoke testing

Confidentiality Agreement : → Non-Disclosure Agreement

Conflict of interest : A situation in which a person or organization is involved in multiple interests, financial or otherwise, and serving one interest could involve working against another. Typically, this relates to situations in which the personal interest of an individual or organization might adversely affect a duty owed to make decisions for the benefit of a third party. †

Connection draining : In load balancing, the allowing of existing requests (in-progress, in-flight) to complete while no new requests are being sent to the respective machine.

Consent Management Platform : A platform that requests, stores, and manages user consent. A CMP helps ensure the privacy of user data in compliance with regulation like the European Union’s GDPR or California’s CCPA/CPRA.

Consistency : In logic, a theory that does not entail a contradiction. †

Console : A computer program designed to be used via a text-only computer interface, such as a text terminal, the command-line interface of some operating systems (Unix, DOS, etc.), or the text-based interface included with most graphical user interface (GUI) operating systems, such as the Win32 console in Microsoft Windows, the Terminal in macOS, and xterm in Unix. A user typically interacts with a console application using only a keyboard and display screen. †

Constant : A value that cannot be altered by the program during normal execution, i.e., the value is constant. When associated with an identifier, a constant is said to be “named,” although the terms “constant” and “named constant” are often used interchangeably. This is contrasted with a variable. †

Constructor : A special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. †

Container : An HTML element that contains other elements.

Containerization : An operating system paradigm in which the kernel allows the existence of multiple isolated user space instances. Such instances, called containers (Solaris, Docker), zones (Solaris), virtual private servers (OpenVZ), partitions, virtual environments (VEs), virtual kernels (DragonFly BSD), or jails (FreeBSD jail or chroot jail) may look like actual computers from the point of view of programs running in them. A computer program running on an ordinary operating system can see all resources (connected devices, files and folders, network shares, CPU power, quantifiable hardware capabilities) of that computer. However, programs running inside of a container can only see the container’s contents and devices assigned to the container. Containerization is used to securely allocate finite hardware resources among a large number of mutually-distrusting users, to consolidate server hardware by moving services on separate hosts into containers on the one server, or to separate several programs to separate containers for improved security, hardware independence, and added resource management features. †

Containing block : The block (element) in which a box resides.

Content : The information and experiences that are directed toward an end user or audience. Content is “something that is to be expressed through some medium, as speech, writing, or any of various arts.” Content can be delivered via many different media including the Internet, cinema, television, radio, smartphones, audio CDs, books, ebooks, magazines, and live events, such as speeches, conferences, and stage performances. † : → Content box

Content box : → Box

Content category : A category that HTML puts elements in. The main categories are metadata content, flow content, sectioning content, heading content, phrasing content, embedded content, and interactive content.

Content Delivery Network : A geographically distributed network of proxy servers and their data centers that has the goal to provide high availability and high performance by distributing the service spatially relative to end users. CDNs came into existence in the late 1990s as a means for alleviating performance bottlenecks of the Internet. They are a layer in the Internet ecosystem. †

Content Management System : A software application that can be used to manage the creation and modification of digital content. CMSs are typically used for Enterprise Content Management (ECM) and Web Content Management (WCM). ECM typically supports multiple users in a collaborative environment by integrating document management, digital asset management and record retention. Alternatively, WCM is the collaborative authoring for websites and may include text and embed graphics, photos, video, audio, maps, and program code that display content and interact with the user. †

Content negotiation : Server- or agent-driven mechanisms that allow to serve different versions of a document (or more generally, representations of a resource) at the same URL, so that user agents can specify which version fits their capabilities the best. Examples include requesting and receiving documents in a preferred language, or media files in a particular format. †

Content network : A network of websites that uses and is accessible through a particular advertising platform, that is, that can be advertised on through the respective ad platform.

Content optimization : The process of improving content, making it as interesting as possible for users and search engines, and increasing its reach.

Content Security Policy : A computer security standard introduced to prevent cross-site scripting (XSS), clickjacking, and other code injection attacks resulting from execution of malicious content in the trusted web page context. CSP provides a standard method for website owners to declare approved origins of content that browsers should be allowed to load on that website—covered types are JavaScript, CSS, HTML frames, web workers, fonts, images, embeddable objects such as Java applets, ActiveX, audio and video files, and other HTML features. † ℹ︎ w3.org/TR/CSP

Content sniffing : → MIME sniffing

Context switch : The process of storing the state of a process or thread, so that it can be restored and resume execution at a later point. Context switching allows multiple processes to share a single CPU, and is an essential feature of a multi-tasking operating system. The precise meaning of the phrase “context switch” varies. In the multi-tasking context, it refers to the process of storing the system state for one task, so that task can be paused and another task resumed. A context switch can also occur as the result of an interrupt, such as when a task needs to access disk storage, freeing up CPU time for other tasks. Some operating systems also require a context switch to move between user mode and kernel mode tasks. The process of context switching can have a negative impact on system performance. †

Continuous Delivery : A software engineering approach in which teams produce software in short cycles, ensuring that the software can be reliably released at any time and, when releasing the software, doing so manually. CD aims at building, testing, and releasing software with greater speed and frequency, and helps reduce the cost, time, and risk of delivering changes by allowing for more incremental updates to applications in production. A straightforward and repeatable deployment process is important for continuous delivery. †

Continuous Deployment : A software engineering approach in which software functionalities are delivered frequently through automated deployments. †

Continuous Integration : The practice of merging all developers’ working copies to a shared mainline (version control) several times a day. †

Continuous Media : Data for which there is a timing relationship between source and destination. The most common examples of continuous media are audio and motion video. Continuous media can be real-time (interactive), where there is a “tight” timing relationship between source and sink, or streaming (playback), where the relationship is less strict. ‡

Contrast : The difference in appearance of two or more parts of a field seen simultaneously or successively (hence: brightness contrast, lightness contrast, color contrast, simultaneous contrast, successive contrast, etc.). Visual information is always contained in some kind of visual contrast, thus contrast is an essential performance (and accessibility) feature of electronic visual displays. †

Control flow : The order in which individual statements, instructions, or function calls of an imperative program are executed or evaluated. †

Convention over Configuration : A software design paradigm used by software frameworks that attempts to decrease the number of decisions that a developer using the framework is required to make without necessarily losing flexibility. The concept was introduced by David Heinemeier Hansson to describe the philosophy of the Ruby on Rails web framework, but is related to earlier ideas like the concept of “sensible defaults” and the principle of least astonishment in user interface design. The phrase essentially means a developer only needs to specify unconventional aspects of the application. †

Conversion : In engineering, the converting of data from one format to another. : In marketing, the converting of visitors to customers (or to visitors who meet another conversion goal).

Conway’s Law : The adage that organizations design systems that mirror their own communication structure. Conway’s Law is named after computer programmer Melvin Conway, who introduced the idea in 1967. His original wording was: “Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization’s communication structure.” †

Cookie : A small piece of data sent from a website and stored on a user’s computer by the user’s web browser while the user is browsing. Cookies were designed to be a reliable mechanism for websites to remember stateful information or to record the user’s browsing activity. They can also be used to remember arbitrary pieces of information that the user previously entered. Cookies perform essential functions in the modern Web. Perhaps most importantly, authentication cookies are the most common method used by web servers to know whether a user is logged in or not, and which account they are logged in with. †

Cookie banner : A web page notification alerting and informing about the respective site’s use of cookies. Cookie banners are common on European websites because of European cookie regulations.

Cookie consent : The agreement to but also a term for the requirement for informing about the use of cookies (also known as a cookie consent form, or cookie banner).

Cookie hijacking : → Session hijacking

CoP : → Community of Practice

CORB : → Cross-Origin Read Blocking

Core Web Vitals : → Web Vitals

CORP : → Cross-Origin Resource Policy

Corporate Design : The official graphical design of the logo and name of a company or institution (or government) used on letterheads, envelopes, forms, folders, brochures, etc. †

Corporate Identity : The manner in which a corporation, firm, or business enterprise presents itself to the public. The corporate identity is typically visualized by branding and with the use of trademarks, but it can also include things like product design, advertising, public relations, etc. Corporate identity is a primary goal of corporate communications, in order to maintain and build the identity to accord with and facilitate the corporate business objectives. †

CORS : → Cross-Origin Resource Sharing

Cost-per-click : → Pay-per-click

Country code top-level domain : An Internet top-level domain generally used or reserved for a country, sovereign state, or dependent territory identified with a country code. All ASCII ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. There are 312 ccTLDs in active use totally. .cn, .tk, .de and .uk contain the highest number of domains. †

Coupling : A state in which one object uses a function of another object. Coupling also describes the degree of interdependence between software modules, as a measure of how closely connected two routines or modules are, and the strength of the relationships between modules. Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion, and vice versa. Low coupling is often a sign of a well-structured computer system and a good design, and when combined with high cohesion, supports the general goals of high readability and maintainability. †

CPA : → Critical path analysis

CPC : → Cost-per-click

CPM : → Critical path method

CQS : → Command-Query Separation

CR : → Candidate Recommendation

Craft : A pastime or a profession that requires particular skills and knowledge of skilled work. †

CRAP : → Create, Replicate, Append, Process

Crawler : An Internet bot that systematically browses the World Wide Web, typically for the purpose of Web indexing (web spidering). Web search engines and some other sites use Web crawling or spidering software to update their web content or indices of others sites’ web content. †

Crawling : The systematic browsing of the World Wide Web for the purpose of indexing. †

Create, Read, Update, Delete : The four basic functions of persistent storage. †

Create, Replicate, Append, Process : A variation of CRUD. †

Critical CSS : The minimum of CSS needed to show a styled web page. Focus is usually on the immediately visible part of a page sitting at the top or “above the fold.” The respective CSS rules are then inlined, that is, embedded in a style element within the page’s head element.

Critical path : The longest stretch of dependent project activities and the time required to complete them from start to finish. †

Critical path analysis : → Critical path

Critical path method : → Critical path

Critical rendering path : A model for the steps needed to render a web page, and optimize its rendering. The critical rendering path includes the building of DOM (Document Object Model) and CSSOM (CSS Object Model), changes to both through the execution of JavaScript, the construction of the render tree, layout, and paint.

CRM : → Customer Relationship Management

cron : A time-based job scheduler on Unix-like computer operating systems. Users that set up and maintain software environments use cron to schedule jobs (commands or shell scripts) to run periodically at fixed times, dates, or intervals. cron is most suitable for scheduling repetitive tasks. Scheduling one-time tasks can be accomplished using the associated at utility. cron was first released in 1975. †

Cron job : A job (command) to be executed by cron.

Crontab : A configuration file that specifies shell commands to run periodically on a given schedule. The crontab files are stored where the lists of jobs and other instructions to the cron daemon are kept. Users can have their own individual crontab files and often there is a system-wide crontab file (usually in /etc or a subdirectory of /etc) that only system administrators can edit. †

Cross-Origin Read Blocking : A security feature that helps mitigate side-channel attacks. CORB prevents the browser from delivering certain cross-origin responses to a web page, for example, when these responses would contain sensitive information.

Cross-Origin Resource Sharing : A mechanism that allows restricted resources on a web page to be requested from another domain outside the domain from which the first resource was served. A web page may freely embed cross-origin images, style sheets, scripts, iframes, and videos. Certain “cross-domain” requests are forbidden by default by the same-origin security policy. CORS defines a way in which a browser and server can interact to determine whether it is safe to allow the cross-origin request. †

Cross-Origin Resource Policy : A policy set by the Cross-Origin-Resource-Policy HTTP header that lets websites and applications opt into protection against certain requests from other origins (such as those issued with elements like <script> and <img>), to mitigate speculative side-channel as well as cross-site script inclusion attacks. CORP is an additional layer of protection beyond the default same-origin policy. ‡

Cross-Origin-Embedder-Policy : An HTTP response header preventing a document from loading cross-origin resources that do not explicitly grant the document permission (using CORP or CORS). ‡

Cross-Site Request Forgery : A type of malicious exploit of a website where unauthorized commands are transmitted from a user that the web application trusts. There are many ways in which a malicious website can transmit such commands; specially-crafted image elements, hidden forms, and JavaScript XMLHttpRequests, for example, can all work without the user’s interaction or even knowledge. Unlike cross-site scripting (XSS), which exploits the trust a user has for a particular site, CSRF exploits the trust that a site has in a user’s browser. †

Cross-Site Script Inclusion : A vulnerability which uses the circumstance that a script referenced through a script element is exempt from the same-origin policy, as scripts need to work across domains. An attacker may access and use what is being loaded using the respective script, and thus leaked across origins.

Cross-Site Scripting : A type of computer security vulnerability typically found in web applications. XSS enables attackers to inject client-side scripts into web pages viewed by other users. A cross-site scripting vulnerability may be used by attackers to bypass access controls such as the same-origin policy. †

Cross-Site WebSocket Hijacking : An attack similar to Cross-Site Request Forgery (CSRF), on a WebSocket handshake, which may allow read/write communication on the respective WebSocket connection. ℹ︎ is.gd/cGQ4bj

CRP : → Critical rendering path

CRUD : → Create, Read, Update, Delete

CSCS : → Customized Scripting in C#

CSP : → Content Security Policy

CSR : → Client-Side Rendering

CSRF : → Cross-Site Request Forgery

CSS : → Cascading Style Sheets

CSS framework : → HTML/CSS framework

CSS lock : CSS code that results in a lower and an upper bound for a particular styling, like a minimum and maximum font size that is otherwise fluid. CSS locks can rely on a single declaration but may include both more declarations as well as media queries. The term “CSS lock” may have first been coined in 2016 by Tim Brown. ℹ︎ is.gd/FjK3B8

CSS Modules : As a CSS Module, a CSS file in which all class and animation names are by default scoped locally. ℹ︎ github.com/css-modules/css-modules

CSS Object Model : A map of all CSS selectors and relevant properties for each selector in the form of tree, with root node, sibling, descendant, child, and other relationships. The CSSOM is similar to the Document Object Model (DOM). Both of them are part of the critical rendering path which is a series of steps that must happen to properly render a website. ‡

CSS preprocessor : A program that allows to generate CSS from the preprocessor’s own unique syntax. There are many CSS preprocessors to choose from, however most CSS preprocessors add features that do not exist in pure CSS, such as mixins, selector nesting, or inheritance selectors. These features make the CSS structure more readable and easier to maintain. ‡

CSS Zen Garden : A web development resource “built to demonstrate what can be accomplished visually through CSS-based design.” Style sheets contributed by web designers and developers from around the world are used to change the visual presentation of a single HTML file, producing hundreds of different designs. Aside from reference to an external CSS file, the HTML markup itself never changes. All visual differences are the result of the CSS (and supporting imagery). CSS Zen Garden is a poster child for CSS-only redesigning. It was created in 2003 by Dave Shea. † ℹ︎ csszengarden.com

CSS-in-JS : A styling technique in which JavaScript is used to style components. When this JavaScript is parsed, CSS is generated (usually as a style element) and attached to the DOM. CSS-in-JS allows to abstract CSS to the component level itself, using JavaScript to describe styles in a declarative and maintainable way. There are multiple implementations of this concept such as styled components or JSS. † ℹ︎ cssinjs.org

CSS-Tricks : A popular web development online magazine and CSS resource. CSS-Tricks was founded in 2007 by Chris Coyier. ℹ︎ css-tricks.com

CSSOM : → CSS Object Model

CSV : → Comma-Separated Values

CSWSH : → Cross-Site WebSocket Hijacking

CTA : → Call to Action

CTR : → Click-through rate

Cumulative Layout Shift : A metric, the so-called layout shift score, for measuring visual stability. The layout shift score is based on a multiplication of impact fraction and distance fraction. ℹ︎ web.dev/cls

curl : A computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various network protocols. The name stands for “Client URL,” which was first released in 1997. † ℹ︎ curl.se

Currying : The technique of converting a function that takes multiple arguments into a sequence of functions that each take a single argument. †

Custom data attribute : An attribute in no namespace whose name starts with the string data-, has at least one character after the hyphen, is XML-compatible, and contains no ASCII upper alphas. Custom data attributes are intended to store custom data, state, annotations, and similar, private to the page or application, for which there are no more appropriate attributes or elements. §

Custom element : → Autonomous custom element : → Customized built-in element

Custom property : A CSS property that is prefixed with --, like --example-name, and whose value can be used in other declarations using the var() function. Custom properties are scoped to the element(s) they are declared on, and participate in the cascade: The value of a custom property is that from the declaration decided by the cascading algorithm. Custom properties are also known as CSS variables. ‡ ℹ︎ w3.org/TR/css-variables-1

Customer Effort Score : A customer service metric that measures the experience with a product or service. Customers document their experience on a 7-point Likert scale ranging from “Very Difficult” to “Very Easy.” The result can be used to assess how much effort is needed to use the respective product or service, and to predict further use.

Customer Relationship Management : An approach to manage a company’s interaction with current and potential customers. It uses data analysis about customers’ history with a company to improve business relationships with customers, specifically focusing on customer retention and ultimately driving sales growth. †

Customized built-in element : A type of custom element for a web component. Customized built-in elements inherit from basic HTML elements. To create a customized built-in element one has to specify which element it extends, and to use it one writes out the basic element but specifies the name of the custom element through an is property. ‡

Customized Scripting in C# : A basic scripting language based on C#. CSCS features no functions, methods, and Boolean values. It was presented in 2016 by Vassili Kaplan. ℹ︎ github.com/vassilych/cscs

Cutting the mustard : The succeeding under difficult circumstances, an expression attributed to BBC developers in the context of user agent detection.

CVE : → Common Vulnerabilities and Exposures

CVS : → Concurrent Versions System

CVSS : → Common Vulnerability Scoring System

Cyan, Magenta, Yellow, and Key : As the CMYK color model, a subtractive color model used in color printing, and also used to describe the printing process itself. CMYK refers to the four ink plates used in some color printing: cyan, magenta, yellow, and key (black). The CMYK model works by partially or entirely masking colors on a lighter, usually white, background. The ink reduces the light that would otherwise be reflected. Such a model is called subtractive because inks “subtract” the colors red, green, and blue from white light. White light minus red leaves cyan, white light minus green leaves magenta, and white light minus blue leaves yellow. †

Cycle time : The amount of time between the start of work on a task to the time it is delivered.

Cyclomatic complexity : A software metric used to indicate the complexity of a program. It is a quantitative measure of the number of linearly independent paths through a program’s source code, and is computed using the control-flow graph of the program. The nodes of the graph correspond to indivisible groups of commands of a program, and a directed edge connects two nodes if the second command might be executed immediately after the first command. Cyclomatic complexity may also be applied to individual functions, modules, methods, or classes. It was developed in 1976 by Thomas J. McCabe, Sr. †

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