The "Do Not Track" feature available in most web browsers is a great option to have if you don't want websites tracking your browsing history. However, as How-To Geek points out, "Do Not Track" provides a false sense of security because it doesn't block as much as you might assume.
As we've discussed before, tracking works by installing third party browser cookies that attempt to target advertisements at you better. The "Do Not Track" option in your browser (Firefox: Preferences>Privacy, Safari: Preferences>Privacy, Chrome: currently unavailable) is supposed to stop this from happening. However, How-To Geek points out the awful truth here:
Enabling "Do Not Track" doesn't change any browser privacy settings. When you enable Do Not Track, your web browser asks each website you connect to please not track you.
The problem is that most websites simply ignore the "do not track" request. Websites have to be updated to pay attention to this field, and most websites aren't interested in obeying it.
If you really don't want to get tracked for advertising, enabling the "Do Not Track" setting in your browser isn't really enough. Instead, you need to take more complicated measures, including grabbing extensions such as Do Not Track Plus, No Script for Firefox and ScriptNo for Chrome. Alternately, you can always use Incognito/Private browsing so your browser doesn't hold onto any data about you.