Google is a search engine that work on the distributed network and thousands of computers and can therefore carry out fast parallel processing. It is very interesting to know how google work. I have show a image that provide you best example of google working.
Google search:
Search is the core technology of the google. The first think if you are searching something in the google then you searching some web sites and web pages and search engine can do this with the a software program that called google spider. Google spider also known as caroler that is responsible to provide a batter out-put to the end user. Spider can fetch web pages and follow the all other web pages link that linked with that pages and store that pages in there indexing aria.
If you want to find something in the google like you need to find information about SEO then you can write your key word SEO information in the google. After then spider can check all there indexing pages in the google data base and find the document that actually related with your key word and helpful to provide a batter search results.