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Who tracks the trackers? Firefox to monitor ad cookies

Stanford University

Browser-tracking Internet "cookies" can be useful, unnecessary, or malicious depending on where they come from — but how are users supposed to know which is which? Mozilla plans to integrate a central list into its Firefox Web browser that takes the guesswork away and makes better privacy automatic.

"Cookies" are tiny files deposited on your computer by websites that allow them to store small amounts of information, such as where you visited on the site, your username and other data.

It's useful to not have to type your login name again to the site you just left 10 minutes ago, but not every site uses this power responsibly. Blocking cookies altogether can make browsing inconvenient, but letting them all in is a privacy risk — and asking about every cookie generated can be tedious and difficult for the user.

Some browsers do this automatically, but their simple rules don't leave room for exceptions — cookies that should be allowed, but aren't for technical reasons, and vice versa.

The Cookie Clearinghouse, created by Stanford's Center for Internet and Society, aims to centralize the cookie-management process by keeping a list of which cookie creators are and aren't to be trusted. Mozilla, which makes the popular Firefox browser, said Wednesday it plans to integrate the system, although which upcoming version will include it has not been announced.

It's not quite a blacklist like an ad-blocker, but rather a way for common exceptions to be taken into account, making sure cookies are useful when they should be, absent when they're not wanted, and otherwise respected when the user makes a specific decision.

The system won't come to the main version of Firefox for a few months at least, so don't worry about looking for it in the options menu just yet.

Devin Coldewey is a contributing writer for NBC News Digital. His personal website is