Lessons from Factorial

You've now seen recursion in action with factorial. Three key observations:

$1.$ The base case ($n = 0$) stops the recursion. Without it, your program crashes.

$2.$ Each recursive call moves closer to the base case (from $n$ to $n-1$).

$3.$ The call stack grows as calls pile up, then shrinks as they return. These patterns repeat in every recursive solution. See them early, and writing recursive code becomes predictable.