Preprocessor

A preprocessor is a program that helps you write computer programs. It takes in your code, which is made up of programming instructions, and changes it so that the computer can understand it. For example, let's say you want to make a computer program that adds two numbers together. You could write your code like this:

sum = number1 + number2

But, the computer won't know what that means. So the preprocessor would change your code to this, so the computer can understand it:

sum = 0
sum = sum + number1
sum = sum + number2

Now the computer totally gets what you want it to do. So that's what a preprocessor does. It takes your code and makes it easier for the computer to understand.