Each time you visit a page on the Internet its a good change that a service on that page is tracking you. Below is a listing of some of the common ways a web page will track you when its being viewed. To view how a website is tracking you, block services, and get a better understanding about each tracking services install Ghostery, a free tool that displays all tracking services and gives you additional details about each service. In the picture to the right, is an example of a Ghostery window being displayed for the CNN website, in this example this page normally has eight services tracking the visit, however, six of the services have been disabled.
How a website may track you
Most sites collect analytical data using services such as Google Analytics to help the owner of a website understand how their web page is being used.
Sites with share buttons from Facebook, Google+, and other social networks will also track each visitor that views the share button or a social network plugin. Users logged into these social services can be tracked and also share the pages through the services.
Many advertisers such as Google (DoubleClick) will track where their advertisement banners are displayed.
Hundreds of other services that monitor traffic, brands, patterns, mobile, etc. for research and advertisers.
Click on the above link to visit and download Ghostery from its website.