What is recursion used for in programming?

Recursion in programming is a method of solving a problem where a function calls itself to solve subproblems until it reaches a base case that stops further calls.

Recursion is useful for tasks that naturally break down into similar sub-tasks, such as:

• Traversing trees and graphs
• Calculating factorials
• Depth-first search
• Solving problems involving partitioning or combinatorics

Example of calculating factorial using recursion in Python:

def factorial(n):
    if n == 0:
        return 1  # base case
    else:
        return n * factorial(n - 1)  # recursive call

print(factorial(5))  # Outputs 120

It is important that a recursive function has a base case, otherwise it will cause infinite calls and lead to a stack overflow error.