Google Personalized Search is a feature of Google Search

Google search

Google or Google Web Search is a web search engine owned by Google Inc. Google Search is the most-used search engine on the World Wide Web, receiving several hundred million queries each day through its various services....

 and provided by Google

Google

Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...

. When a user is logged into a Google Account

Google Account

A Google Account is a user account that provides access to Google-owned services such as Blogger, YouTube, and Google Groups. A Google Account can be identified either by the username or by their unique permanent ID...

, all of their searches on Google Search are recorded into Google Web History

Google Web History

Google Web History is a feature of Google Search and provided by Google, in which all search queries and results that a user clicks on are recorded to. The feature is only available for users logged in to a Google Account. The feature was renamed from Search History to Web History on April 19, 2007...

. Then, when a user performs a search, the search results are not only based on the relevancy of each web page

Web page

A web page or webpage is a document or information resource that is suitable for the World Wide Web and can be accessed through a web browser and displayed on a monitor or mobile device. This information is usually in HTML or XHTML format, and may provide navigation to other web pages via hypertext...

 to the search term, but the service also takes into account what websites the user previously visited through search results to determine which search results to determine for future searches, to provide a more personalized experience. The feature only takes effect after the user has performed several searches, so that it can be calibrated to the user's tastes.

History

The feature was originally introduced with a test version, which was available on March 29, 2004. Later, Personalized Search was made available as a service on April 20, 2005, at the time still separate from Google Search. The feature was first introduced to Google Search on June 28, 2005, to users with Google Accounts. Originally a part of Google Labs

Google Labs

Google Labs was a page created by Google to demonstrate and test new Google projects. Google calls Google Labs,Google also uses an invitation-only phase for trusted testers to test projects including Gmail, Google Calendar and Google Wave and many of these have their own "labs" webpages for...

 as a beta product, the feature graduated from Labs on November 11, 2005, and become a part of the normal Google Search. On December 4, 2009, Personalized Search was introduced to all users of Google, including those who are not logged in to a Google Account.

Reception

Several concerns have been brought up regarding the feature. It decreases the likelihood of finding new information by biasing search results towards what the user has already found. It introduces potential privacy problems in which a user may not be aware that their search results are personalized for them, and wonder why the things that they are interested in have become so relevant. The feature also has profound effects on the search engine optimization

Search engine optimization

Search engine optimization is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid search results...

industry, due to the fact that search results will no longer be ranked the same way for every user.