Google: All the Things!

The fact that there are many sets of these servers around the country & world allows Google to work so quickly. 

It also occasionally means that you’ll get different search results for the same search only minutes apart. 

Google has a great explanation of how it works here. 

Short answer: the more pages that link to a page, the higher up the search rankings that page goes

• More Info:

  • The links from well-linked and well-respected pages are given more weight

  • When many pages link to each other, it can (but does not always) skew the rank.  

Page Rank – Wikipedia Article

Google Search Central – This is Google's faq about page ranking.

Google Page Rank Checker – This lets you see the page ranking of any website.