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
ChaCha (search engine) April 2009, Rick Reilly spent some time working for ChaCha for an article on "ESPN The Magazine". ChaCha (search engine) ChaCha was a human-guided search engine. It provided free, real-time answers to any question, through its website, or by using one of the company's mobile apps. The company, founded in 2006 by Scott A. Jones and Brad Bostic, was based in Carmel, Indiana, United States, part of the Indianapolis metropolitan area. Its name comes from the Mandarin Chinese word "cha" (), which means "to search." ChaCha answered questions through the use of independent contractors called Guides. Guides were paid $0.02