Utma, utmb, utmz cookies

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Revision as of 16:14, 19 January 2011 by (Talk)

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These are primarily notes
It won't be complete in any sense.
It exists to contain fragments of useful information.

These cookies track visits on sites that use Google Analytics.

The cookies named
are part of Google Analytics, originally by the urchin tracking module, also by the newer ga.js.

Some details:

  • __utmz tracks where a visitor came from (search engine, search keyword, link)
  • __utma tracks each user's amount of visits, first, last visit.
  • __utmb and __utmc are used to track when a visit starts and approximately ends (c expires quickly). If you look at cookie state changes (e.g. using firecookie), you will see these change regularly.


  • __utmv is used for user-custom variables in Analytics
  • __utmk - digest hashes of utm values (verify)