HOW GOOGLE SEARCH ENGINE WORKS!!!

   hi friends many of us wonders about googe search's speed .When i searched  how google search engine works "GOOGLE" site itself provides how it works .When i start to read about that i observed
they are using a method called CRAWLING .
    HERE THIS LINK SHOWS HOW IT EXACTLY WORKS
http://www.google.co.in/intl/en/insidesearch/howsearchworks/thestory/