Why do search engines store search history?

Not all search engines, for example Duck Duck Go, store search history but others, including Google and Bing, do. Why do some search engines store search history?

Purpose of search history

Their are two main reasons why search engines store search history:

User viewpoint
17% of people have not been able to return to a webpage they once visited which can be problematic for web searchers. Storing search history helps the searcher to relocate websites they once visited.
Search engine viewpoint
Bing, Google and Yahoo, for instance, use search history to help personalise results because past results are assigned to a user profile, helping search engines build picture’s of your likes and dislikes.
It is also important to note that search history makes identity theft and snooping easier. Search history, furthermore, allows governments to find out what you have been searching. PRISM is the latest development for governments to obtain information on what and when you search for information.

Photo of PRISM’s logo. Source.

Finding information

Our search behaviour is influenced by 3 things:

  • Individual user character
  • Type of search task
  • Relevance of search results

Using think aloud protocol one study found that 51% of users look at organic results and ignore PPC adverts. However, adverts are examined if organic results do not return relevant answers.

Whenever most of us search for information we are biased towards high rankings. So top results matter because click-through rates are higher for the top 10, in particular the top 3, results.

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  1. Anonymous (2005) Google service remembers every search. Information Management Journal. 39(4) pp. 8–8
  2. Graphic, Visualation and Usability Center. GVU’s Tenth WWW User Survey. October 1998.
  3. Jansen, B.J. Brown, A. and Resnick, M. (2007) Factors relating to the decision to click on a sponsored link. Decision Support Systems. 44[issue number missing] pp. 46–59
  4. Joachims, T. Granka, L. Pan, B. Hembrooke, H. and Gay, G. (2005) Accurately interpreting clickthrough data as implicit feedback. In Proceedings SIGIR. pp. 145 — 161

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