The Functions are an important part of programming in C. They allow you to divide your program into smaller, reusable blocks of code. This makes your program easier to read and maintain. A function declaration (also called a prototype) tells the compiler the function’s name, return type, and the types of its parameters. It does not contain the actual code, just the information needed to call the function. The function definition contains the full code, explaining what the function does.

For example, this is a declaration of a function named add that takes two integers and returns an integer:

int add(int a, int b);