As with much of what is in this blog, for just about everything a footnote could be added with some exception/alternative explanation/..., but I will resist the urge to do so.
The following picture shows some of the important concepts to keep in mind... especially when reading emacs documentation. Of course, many of the visual details depend on your color settings, operating system, emacs-version and so on...
The following table is another way to help you understand the emacs jargon:
|emacs terminology||common terminology|
|evaluate expressions||interpret/execute some code|
|font locking||syntax highlighting|
|mark||beginning of the selected area|
|mode line||status bar|
|region||selected area; the area between 'mark' and 'point'|
|visit a file||open a file|