Preprocessor Directive
This is used to use a certain code, that are programmed by someone else and stored in the form of libraries.
Main Function
the main piece of code, where actual code is written, c++ requires us to write this otherwise, the computer will ignore our program and not compile it
Expression statement
they are basic expression used for doing processes like assigning a value to variable, outputting values to the user and doing simple math
Declaration statement
used for declaring variables and assigning initial values to them
Return statement
used for returning a value to the computer, that will stored in the computer. in our case we dont want anything to be stored, so we return 0