Definition of

Logarithm

A logarithm answers the question "How many of this number do we multiply to get that number?"

Example: How many 2s must we multiply to get 8?
Answer: 2 × 2 × 2 = 8, so we had to multiply 3 of the 2s to get 8

We say the logarithm of 8 with base 2 is 3

In fact these two things are the same:

 logarithm example