Google Personalized Search

Google Personalized Search is a personalized search feature of Google Search. All searches on Google Search are associated with a browser cookie record. Then, when a user performs a search, the search results are not only based on the relevance of each web page to the search term, but also on which websites the user (or someone else using the same browser) visited through previous search results. This provides a more personalized experience that can increase the relevance of the search results for the particular user, but also has some side effects, such as informing other users of the same IP address or computer about what others have been searching for, or creating a filter bubble. The feature only takes effect after several searches have been recorded, so that it can be calibrated to the user's tastes.

Personalized Search was originally introduced on March 29, 2004 as a beta test of a Google Labs project. On April 20, 2005, it was made available as a non-beta service, but still separate from ordinary Google Search. On November 11, 2005, it became a part of the normal Google Search, but only to users with Google Accounts.

Beginning on December 4, 2009, Personalized Search was applied to all users of Google Search, including those who are not logged into a Google Account.

In addition to customizing results based on personal behavior and interests associated with a Google Account, Google also implemented social search results in October 2009 based on people whom one knows. Operating on the assumption that one's associates share similar interests, these results would give a ranking boost to sites from within a user's "Social Circle". These two services integrated into regular results by February 2011 and expanded results by including content shared to users known through social networks.

Google's search algorithm is driven by collecting and storing web history in its databases. For non-authenticated users Google looks at anonymously stored browser cookies on a user's browser and compares the unique string with those stored within Google databases. Google accounts logged into Google Chrome use user's web history to learn what sites and content you like and base the search results presented on them. Using the data provided by the user Google constructs a profile including gender, age, languages, and interests based on prior site traffic.

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