A function is a set of statements that take inputs, do some specific computation, and produce output. The idea is to put some commonly or repeatedly done tasks together and make a function so that instead of writing the same code again and again for different inputs, we can call the function.

In simple terms, a function is a block of code that only runs when it is called.

• Functions help us in reducing code redundancy. If functionality is performed at multiple places in software, then rather than writing the same code, again and again, we create a function and call it everywhere. This also helps in maintenance as we have to change at one place if we make future changes to the functionality.
• Functions make code modular. Consider a big file having many lines of code. It becomes really simple to read and use the code if the code is divided into functions.
• Functions provide abstraction. For example, we can use library functions without worrying about their internal work.

Related Article : https://www.geeksforgeeks.org/functions-in-cpp/