Explain recursion simply?

Recursion is a programming technique where a function calls itself to solve a problem. It typically involves two main components:

1. Base Case: This is the condition under which the recursion stops. It prevents infinite loops.
2. Recursive Case: This is where the function calls itself with a modified argument, gradually approaching the base case.

Example:

Here's a simple example in Python that calculates the factorial of a number:

def factorial(n):
    if n == 0:  # Base case
        return 1
    else:       # Recursive case
        return n * factorial(n - 1)

print(factorial(5))  # Output: 120

In this example, factorial calls itself with n - 1 until it reaches the base case of n == 0.