Search engine optimization different signals. The leading search engines, Google, Bing, and Yahoo, do not disclose the algorithms they use to rank pages. Some SEO practitioners have studied different approaches to search engine optimization, and have shared their personal opinions. Patents related to search engines can provide information to better understand search engines. In 2005, Google began personalizing search results for each user. Depending on their history of previous searches, Google crafted results for logged in users. In 2007, Google announced a campaign against paid links that transfer PageRank. On June 15, 2009, Google disclosed that they had taken measures to mitigate the
Distributed search engine Distributed search engine A distributed search engine is a search engine where there is no central server. Unlike traditional centralized search engines, work such as crawling, data mining, indexing, and query processing is distributed among several peers in a decentralized manner where there is no single point of control. In April 2000 several programmers (including Gene Kan, Steve Waterhouse) built a prototype P2P web search engine based on Gnutella called InfraSearch. The technology was later acquired by Sun Microsystems and incorporated into the JXTA project. It was meant to run inside the participating websites' databases creating a P2P network that