To see what is probably only the tip of an iceberg of information Google is collecting about you, log in to your Google account and go to "Ads Settings". There it is, your simple profile based on your behavior online. This doesn’t mean that companies like Google use the profile they’ve complied about you to your disadvantage. However, it’s important to understand the extent of the collected information and the potential for that information to be shared—knowingly or not—with other entities. Unlike the NSA, private companies like Google are not subject to public scrutiny, oversight, or strict regulations—and no—not even some degree of transparency. To better understand Google’s attitude toward people using their services, it’s best to think of them as the largest marketing company in the world, since most of its revenue is generated through online advertising.
What Google tracks:
- Your search history;
- What pages you visited on a site, in what order, how long you stayed there, more;
- Your location;
- Your interests and demographics;
- Your search trends;
- Your Gmail information.
One of the many things you can do to reduce Google’s collection activities is to change the "Ads Setting." Assuming that you trust that Google will honor your opt-out preference and stop following you everywhere on the Internet, go to Ads Settings and opt out under “Opt-out settings.” You can opt out from Google’s personalized ads settings even if you are not logged in to your account, because Google sets a cookie in your web browser and tracks your movements on the Internet even if you are not logged in to a Google account.
To learn more read "15 ways Google monitors you" in U.S. New & World Report.
The Huffington Post published a detailed article on things you can do to limit how much of your activities are tracked not only by Google, but also by Bing and Yahoo, which collect just as much information as does Google.