Can reveal the user's surfing habits.
Most browsers logs the URLs a user has visited. This history is taken care of in a period which in many cases, the user can decide the length of. This can in many ways be practical for the user, especially when entering URLs in the address field. If you have visited the site before, your readers may fill out the rest of the URL once the user has entered the first part.
But the content of Web pages can be influenced by history. Links to web pages you have visited before, is often shown with a different color or style than non-visited links. How do the links look like, can be determined using a stylesheet (CSS).
The problem in most browsers is that the information about whether the links have been visited or not, is available via the Web site that links are displayed. Such information can be gathered using the JavaScript functions that getComputedStyle ().
Challenges is that you can not simply turn off this option without the users lose function.
Mozilla has been clear over the issue since 2002, when a notice
was posted to Bugzilla.