UTM - Urchin Tracking Module
Urchin Tracking Module or UTM, is a query parameter added to a URL to help track where a user is coming from.
This is used in marketing as a way to gauge the success of various sources (Twitter, Facebook, etc) and content types and use the data as a way to make better decisions about future marketing efforts.
How It Works
An example of a UTM:
In this example, if someone were to visit my website with this link, the query parameter would be used in my analytics software to attribute the visitor to the source of twitterShare on Twitter