Google Analytics - Event Tracking
Analytics data is typically page based - when a visitor downloads a page from your site it counts as a page view.
With the growth of web interactivity, online video and interactive Flash tools however page views often no longer fully capture a visitors interaction with your site. For example, if you have an embedded video and a user clicks "Play" simply monitoring page views would fail to show how many visitors go on to play the video and how many watch it to the end.
This is where Google Analytics Event tracking code comes in.
Visitors to a page for example who opt to play an embedded video are considered to have had further interaction with your site and thus even if they only look at one page they would not be considered to have bounced.
It is not currently possible to view events as website goals but this may well be added to Analytics in the future. Use of Google Analytics Custom Reporting tools however can provide useful insight in combination with event tracking data.