Best Firefox trick: Toss your cookies

If Firefox had no other special feature, I’d use it as my preferred web browser just for its cookie handling options.

For those of you who came in late, a “cookie” is a scrap of data that may be placed on your computer when you visit a web site. Web sites can only read and write their own cookies.

Used responsibly, cookies are very useful. For instance, most retail sites use cookies to keep track of the contents and status of your shopping cart.

Unfortunately, cookies are also subject to abuse. The most infamous examples are the so-called “tracking cookies.” Many web pages display advertising served up from third-party web sites. These third-party ad networks also deposit cookies on your computer. If you later visit another web site using ads from one of these outfits, they will read and update their cookies, in the process collecting information on what sites you’ve been visiting, what you looked at while you were there, the IP address you are using to access the Internet, the particulars of your web browser and a fair bit of information about your computing environment. The marketing droids say this is harmless and even beneficial because it enables them to provide advertising you are more likely to find useful based on your interests. Personally, I find it creepy that some anonymous outfit is building a profile of my browsing habits.

Some people deal with this by controlling what web sites are allowed to set cookies on their machines and under what circumstances. This gets tedious and often finicky. I prefer an easier approach.

Since its first release, Firefox has had an option to delete all cookies when you close the browser. Web sites can set any cookies they wish; everything works normally. When you exit Firefox, all the cookies disappear. Simple. Here’s how you do it in Firefox 3.5. Earlier and later versions are similar…

1. From the Firefox Tools menu, Choose “Options…”
2. Select the Privacy tab.
3. In the History section of the Privacy window, tell Firefox to “Use custom settings for history”, put checkmarks next to “Accept cookies from sites” and “Accept third-party cookies”, and select the option to keep cookies until “I close Firefox”. You should end up with a Privacy pane that looks something like this:
   
4. Click the “Show Cookies…” button and go delete all your existing cookies. You may be surprised at how many are stored on your computer.
5. Click the “OK” button to save your changes.

So, what’s the downside? Well, there are still a few web sites out there that store personalization information in cookies. Deleting your cookies every time you close out of Firefox will break these sites. However, this style of “portal” site went out of fashion quite some time ago. These days, most user-customized web sites store the personal settings on their servers and retrieve them when the user logs into the site.

For most people, the “toss your cookies” Firefox setting increases privacy with no significant effect on their web browsing experience.