What is a recursion in the (simplest definition possible)

Question

Can someone explain what exactly a recursion is but in a way that anyone can understand?

I'm trying to find out what a recursion is

Answer 1

Recursion is the process of solving a problem by applying the same procedure to progressively smaller subsets of the original problem until a trivial case is reached. The basic example for this is finding the nth Fibonacci number:

func Fibonacci(n int)
    if n = 0
        return 0
    elif n < 3
        return 1
    else
        return Fibonacci(n - 1) + Fibonacci(n - 2)

This function works by calling itself for values of n that are equal to or greater than 3. This is called the recursive case. The other two situations (n = 0 or 3 > n > 0) are called base cases and provide a stop condition for the recursion.

All recursive functions can be written using a looping structure, but this is usually a fairly complicated process.

I'd say this provides a decent layman's explanation as well.