What searching algorithm/concept is used in Google?

Question

What searching algorithm/concept is used in Google?

Answer 1

Inverted index and MapReduce is the basics of most search engines (I believe). You create an index on the content and run queries against that index to display relevance. Google however does much more than just a simple index of where each word occurs, they also do how many times it appeared, where it appears, where it appears in relation to other words, the ordering, etc. Another simple concept that's used is "stop words" which may include things like "and", "the", and so on (basically "simple" words that occur often and generally not the focus of a query). In addition, they employ things like Page Rank (mentioned by TStamper) to order pages by relevance and importance.

MapReduce is basically taking one job and dividing it into smaller jobs and letting those smaller jobs run on many systems (in parts for scalability and in parts for speed). If I recall correctly, Google was able to make use of "average" computers to distribute jobs to instead of server-grade computers. Since the processing capability of one computer is reaching a peak, many technology are heading towards cloud computing where a job is done by many physical machines.

I'm not sure how much searching Google does, it's more accurately crawling. The difference lies in that they just start at specific points and crawl to anything reachable and repeat until they hit some sort of dead-end.