Google is the most preferred search engine on the Internet. So how does Google return its search results in a matter of seconds?
Google has 3 areas on which it focuses. Apart from Search, which is its core technology area, it also focuses on Ads and Apps. Ads are its central business proposition ie. how it makes money. Apps are the umbrella over its web-based software that you can access anywhere, any time.
This interesting video will throw some light on how search works.