Address @tautschnig's comments.

Author: johanneskloos

doc/architectural/background-concepts.md

@@ -11,7 +11,7 @@ three important analysis methods and some commonly used terms.
 \section representations_section Representations
 
 One of the first questions we should be considering is how we represent programs
-in such a way that we can easily analyze and reason them.
+in such a way that we can easily analyze and reason about them.
 
 As it turns out, the best way to do this is to use a variety of
 different representations, each representing a different level of
@@ -81,12 +81,12 @@ The key data structure that stores the result of this step is known as an
 (cf. [Wikipedia](https://en.wikipedia.org/wiki/Abstract_syntax_tree)).
 ASTs are still relatively
 close to the source code, and represent the structure of the source code
-while abstracting away from irrelevant details, e.g., dropping
+while abstracting away from syntactic details, e.g., dropping
 parentheses, semicolons and braces as long as those are only used for
 grouping.
 
 Considering the example of the C program given above, we first notice
-that the program describes (in C terms) a single *compilation unit*,
+that the program describes (in C terms) a single *translation unit*,
 consisting of four top-level *declarations* (the two function forward
 declarations of `atoi` and `printf`, and the function definitions of
 `factorial` and `main`). Let us start considering the specification of
@@ -112,9 +112,9 @@ it has a child node initiating a parameter list, and there is a node in
 the parameter list for each parameter, giving its type and name, if a
 name is given.
 
-More interestingly, we can represent the structure of the `factorial`
+Extending this idea, we can represent the structure of the `factorial`
 function using ASTs. The idea here is that the code itself has a
-hierarchical structure. In the case of C, this start with the block
+hierarchical structure. In the case of C, this starts with the block
 structure of the code: At the top, we start with a block of code, having
 three children, each being a ''statement'' node:
 1. `unsigned long fac = 1`