How Google works
"Hey Google, I have a question!"
Google's Web Server
Google web servers send a query to the index servers. The content inside the index servers is similar to the index in the back of a book—it tells which pages contain the words that match the query.
The query travels to the doc servers, which actually retrieve the stored documents. Snippets are generated to describe each search result.
The search results are returned to the user in a fraction of a second.