Algorithm behind typo corrections in Google Search

Question

I notice if I make a typo in Google search bar, it is very likely to correct it for me.

Like, if I type "incerdible", it will suggest "incredible", or for "stackovflow", it will be "stackoverflow".

What is the core idea of such algorithm?

Answer 1

Here is an explanation, and some more links with further details:

http://norvig.com/spell-correct.html