functions that call themselves

A recursive function is one that calls itself.

The two parts of a recursive function

A correctly written recursive function has:

What does it mean to move towards the base case


parameter to function base case progress towards the base case
a list called alist if alist==[] (empty list) recursive call on a shorter list (e.g. (alist[1:] or alist[:-1])
a string s if s=="" (empty string) recursive call on a shorter string (e.g. (s[1:] or s[:-1])
a positive integer n if n==0 recursive call on n-1