Understanding How Search Engines Work

All the major search engine operate in a similar manner so to master search engine optimisation it is good to understand how the search engines work and how they determine the order of websites in SERPs.  Search engines have a short list of critical operations that allows them to provide relevant web results when searchers use their system to find information;

1. Crawling the Web
   Search engines run automated programs, called “spiders” that use the link structure of the web to crawl the web pages and documents that make up the World Wide Web.
2. Indexing Documents
   Once a page has been crawled, it’s contents can be “indexed” – this means they are stored in a huge database where they can be analysed in a minute fraction of a second.
3. Processing Queries
   When a user enter a search term into a search engine (performed hundreds of millions of times each day), the search engine retrieves all documents from its index that match the search term.
4. Ranking Results
   Once the search engine has determined which results are a match for the search term, the engine’s algorithm (a complex mathematical equation commonly used for sorting) runs calculations on each of the results to determine which is most relevant to the given query. They sort these on the results pages in order from most relevant to least so that users can make a choice about which to select.

Although a search engine’s operations are not particularly lengthy, systems like Google, Yahoo, Bing and MSN are among the most complex, processing-intensive computers in the world, managing millions of calculations each second and funneling demands for information to an enormous group of users.