__utmz Cookie: What is It & What Does it Do?

Table of Contents

The __utmz cookie is part of the Google Analytics tracking system and is used to store information about the traffic source or campaign that explains how a user reached your site. Here’s a breakdown of what the __utmz cookie does and its components:

UTMZ Cookie
  • Tracks Traffic Sources: The primary function of the __utmz cookie is to keep track of where visitors came from, what search engine was used, what link was clicked on, what keyword was used, and where in the world the visitor is located when they access the website.
  • Campaign Information: It helps in tracking the performance of marketing campaigns and traffic sources over time, allowing website owners to analyze the effectiveness of their marketing efforts.

The __utmz cookie typically stores several pieces of information, encoded in a string. This includes:

  • Timestamp: The time at which the cookie was set.
  • Session Number: The session number of the visit.
  • Campaign Number: The number of the campaign that brought the user to the site.
  • Campaign Source: The source of the traffic, e.g., search engine (google), direct, referring site.
  • Campaign Medium: The medium of the traffic, e.g., organic, CPC (cost per click), email.
  • Campaign Term: The search term used if the visitor came from a search engine.
  • Campaign Content: Used for A/B testing and content-targeted ads to specify the version of a link or ad that was clicked.

Cookie Lifespan

The __utmz cookie typically has a lifespan of six months but this can vary depending on the website’s configuration and how frequently users visit the site. It gets updated with each page view if a user enters the site from a different source.

Importance in Analytics

By analyzing the data stored in the __utmz cookie, website owners and marketers can gain insights into how users are finding their site and which marketing strategies are most effective. This helps in making informed decisions about where to allocate marketing resources and how to improve user acquisition strategies.

Managing and Deleting the __utmz Cookie

Users can manage and delete cookies through their browser settings. Deleting cookies may impact the user’s experience on a site and the accuracy of traffic data collected by Google Analytics.

Understanding the role of the __utmz cookie is crucial for anyone involved in web analytics and digital marketing, as it provides valuable insights into user behavior and the effectiveness of marketing efforts.

An example value of the __utmz cookie might look like this:


This string can be broken down as:

123456789.123456789: Cookie domain hash and timestamp.
1.1: Number of sessions and campaign number.
utmcsr=google: Traffic source.
utmccn=(organic): Campaign name (in this case, it is organic search).
utmcmd=organic: Campaign medium (organic search).
utmctr=keyword: Search term used.

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