Cookie Usage
From Google’s information about the cookies the system sets in your browser:
Google Analytics code uses first-party cookies to:
- Determine which domain to measure
- Distinguish unique users
- Remember the number and time of previous visits
- Remember traffic source information
- Determine the start and end of a session
- Remember the value of visitor-level custom variables
Google Analytics sets the following cookies:
_utma
Used to distinguish users and sessions. The cookie is created when the javascript library executes and no existing __utma cookies exists. The cookie is updated every time data is sent to Google Analytics.
Default expiration time: 2 years from set/update.
_utmb
Used to determine new sessions/visits. The cookie is created when the javascript library executes and no existing __utmb cookies exists. The cookie is updated every time data is sent to Google Analytics.
Default expiration time: 30 minutes from set/update.
_utmc
Not used in ga.js. Set for interoperability with urchin.js. Historically, this cookie operated in conjunction with the __utmb cookie to determine whether the user was in a new session/visit.
Default expiration time: End of browser session.
_utmz
Stores the traffic source or campaign that explains how the user reached your site. The cookie is created when the javascript library executes and is updated every time data is sent to Google Analytics.
Default expiration time: 6 months from set/update.
_utmv
Used to store visitor-level custom variable data. This cookie is created when a developer uses the _setCustomVar method with a visitor level custom variable. This cookie was also used for the deprecated _setVar method. The cookie is updated every time data is sent to Google Analytics.
Default expiration time: 2 years from set/update.
Taken from
https://developers.google.com/analytics/devguides/collection/analyticsjs/cookie-usage
You can use your browser’s settings to prevent this, or any, site setting cookies, though be aware that some sites may rely on cookies to function properly. Google has also developed a browser add-on that allows you to turn off Google Analytics completely for your browser:https://tools.google.com/dlpage/gaoptout?hl=en