How to use the Google Analytics event tracking report, according to Search Engine Watch.
The majority of reports in Google Analytics are made up of data that is automatically collected with the basic Google Analytics code on your website.
There are a few areas where you can add additional information into Google Analytics on top of this to get data specific to your website and events is one of them. Its called Events because it is most often used to measure actions (aka, events) happening on your website.
From clicks on a button, to form submissions, video interaction, or scrolling to the bottom of the page, Event Tracking can be used for all manner of activity measurement on your website.