C++ Course. Explain Statements etc. in my own words!

Ok, so this is mostly for myself, to track progress but feel free to comment if you feel like it. It’s my first post so let’s do this!
Preprocessor Directive: I think this is where it goes into a library, gets someone elses code so we can use things like cout in our code!
Expression statements: These are statements where we can express ourselves within a program through sentences etc.
Declaration statements: These are statements where you can declare things like variables with for example numbers!
Hope I got 'em right lol