Recursion

Recursion is the process a procedure goes through when one of the steps of the procedure involves invoking the procedure itself

i.e.

def factorial(x):
 
    if x == 1:
        return 1
    else:
        return (x * factorial(x-1)) # RECURSIVE LINE
 
 
num = 3
print("The factorial of", num, "is", factorial(num))