This is telling the compiler to copy the code from the iostream header file before compiling the rest of the code.
The operating system looks for the main function when the program runs.
It’s the starting point of the program.
Without it the program will not build.
These are for printing messages to the terminal for the player to read and for storing the code the player enters.
These are for reserving the places in the computer’s memory for the codes the player will enter.
The return statement in the main function is necessary because the value returned is used as an exit status for the operating system.