What is tail recursion optimization? [duplicate]

Question

Possible Duplicate:
What is tail-recursion?

What is tail recursion optimization?

Answer 1

a calls b calls c calls d.

at the end you have tails:

d returns to c returns to b returns to a. if all these do nothing (like in recursion, where it is actually a calls a calls a calls a) then you can optimize that... ...into d returns to a.