"Memoization" is not a misspelling of "memorization."

Let F(n) be the nth Fibonacci number.  We can recursively define
F(n) = F(n-2) + F(n-1).  Assume, for the moment, that adding or
multiplying two integers takes O(1) time, regardless of the size
of the integers.  (This is not realistic for very large numbers,
but we can then worry about that cost later.)

1.  You can find F(n) using recursion in O(F(n)) time by recursion.

2.  You can find F(n) in O(n) time by dynamic programming.

3.  You can find F(n) in O(log n) time by memoization.