Google now explain there Business via These three videos in very nice manner . there are main three principles behind this is : Search ,apps , and Ads.
according to Google Search is our core part , apps is main umbrella over all the software and Ads is a central business proposition.
Now you can see how Search get works :
google Creats a Index of each web pages and manage them according to the category and evaluating that more than 200 Quality factor.as you can see google produces search in fraction of time,now you can think you fast there indexing is ?
How Google Apps get work:
till now google get introduces thousands of application or tools . all the application data is stores online, so its not specific to one computer.you can download that file anywhere on your mobile as well as on your pc too.
How Google search ads works :
when you do search with google web search , that time you can see ads are also showing according to there results and all . ads search result offering very useful information for commercial queries . look at the below videos on how it exactly works.
hope you like this videos , you can see it on http://www.google.com/howgoogleworks