_utmz Google Analytics Cookie Demystified

Google Analytic drops few cookies that help them produce the nice reports that you in Google Analytics.  One of those cookies is _umtz.  This cookie is used to determine the sources visitor used to visit your site   Below is an explanation of this cookie.

_utmz cookie consists of  5 parts separated by “.”

  1. A hash key that identifies the domain and is unique for each domain
  2. Timestamp of the visit via that source
  3. Total visits by the visitor
  4. Total number of sources the visitor has come from over the life of the cookie
  5. Details about the source (campaign, source, medium, content, keyword)

The final cookie looks like this

[domain identifier].[unique visitor id].[timstamp when cookie is set].[number of visits].[number of sources visitor has used to visit the site].[details about the source]

Details about the source:  All the variables that you can set in a campaign are set in this part of the cookie (see the image below, I will write more about campaigns in a future post)

Note: Cookie is set every time a visitor uses a new source to If a cookie is already set with value then direct visit won’t overwrite it.

Related: _utma Google Analytics Cookie Demystified

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