How Can I Finally Understand What Functions Do?

Learn functions in small steps: first make one that simply prints a message, then make one that returns a value, and finally make one that accepts arguments. Also remember that defining a function usually does not run its body immediately; the code executes when you call the function by its name.

The biggest practical benefit is avoiding duplicated code. Suppose your program needs to check whether someone is an adult in several places. You can write `isAdult(age)` once and use it everywhere. If the rule needs fixing later, you change the function in one place instead of hunting through the whole program.

A function is like a recipe or a reusable set of instructions. You give it a name, define the steps once, and then call that name whenever you need those steps again. It can accept inputs, such as ingredients, and may produce an output, such as a finished dish.

Think of a function as a machine. You put inputs into it, it performs a specific process, and it may give you a result. For example, `add(3, 4)` takes two numbers and returns `7`. The important parts are defining the machine and calling it when you want it to run.