Google

Online search engine for the web

• over 10 billion web pages indexed
• each search returns results in an automatically ranked order
• google hardware consists of tens of thousands of processors

Main Features

• Ranking performed using the page-rank algorithm

Trust/authority

• Anyone can create a webpage on any topic at any time
• SO, Results are NOT trustworthy without first checking sources, etc.
• Results are often very useful and can be checked
• Page rank is constantly tuned to make it blind to manipulation

Page Rank Algorithm

To find the pagerank of page X, you need to take a weighted average of all page that link to X, more precisely, we have


from S. Brin and L. Page. Anatomy of a large-scale hypertextual web search engine. In Proc. 7th Int'l World Wide Web Conference, 1998.
The actual page rank is more sophisticated and estimates the importance of the link among other factors.