an expression statement is a line of code that is finished off with a semicolon, and where we do not declare variables.
a declaration statement is a line of code that is finished off with a semicolon, and where we declare variables.
the role of the preprocessor directive is to instruct the compiler to use a header file in our “cpp” file. it starts with a hash.
our program starts off within the main function. Without this function, we cannot run the program.
a return statement indicate the end of the program.