"Cookies" are tidbits of information that Web sites store on your computer, temporarily or more-or-less permanently. In many cases cookies are useful and innocuous.They may be passwords and user IDs, so that you do not have to keep retyping them every time you load a new page at the site that issued the cookie.

Other cookies however, can be used for "data mining" purposes, to track your motions through a Web site, the time you spend there, what links you click on and other details that the company wants to record, usually for marketing purposes.

Most cookies can only be read by the party that created them. However, some companies that manage online banner advertising are, in essence, cookie sharing rings. They can track which pages you load, which ads you click on, etc., and share this information with all of their client Web sites (who may number in the hundreds, even thousands.) Some examples of these cookie sharing rings are DoubleClick, AdCast and LinkExchange

Browsers are starting to allow user control over cookies. Netscape, for example, allows you to see a notice when a site tries to write a cookie file to your hard drive, and gives you some information about it, allowing you to decide whether or not to accept it. (Be on the lookout for cookies the function of which is not apparent, which go to other sites than the one you are trying to load, or which are not temporary).

It also allows you to automatically block all cookies that are being sent to third parties (or to block all cookies, entirely, but this will make some sites inoperable). Internet Explorer has a cookie management interface in addition to Netscape-like features, allowing you to selectively enable or disable cookies on a site-by-site basis, even to allow cookies for a site generally, but delete a specific cookie you are suspicious about.

With Internet Explorer you can also turn on cookies for a site temporarily then disable them when you no longer need them (e.g., at an online bookstore that requires cookies to process an order, but whom you don't want to track what books you are looking at, what links you are following, etc., the rest of the time.) Turning on cookie warnings will cause alert boxes to pop up, but after some practice you may learn to hit "Decline" so fast that you hardly notice them any more. The idea is to only enable cookies on sites that require them AND whom you trust. You may also wish to try out "alternative" browsers like Mozilla (Windows, Mac, Linux), Opera (Windows, Mac, Linux), Konqueror (Linux), and iCab (Mac), which may offer better cookie management.

There are also numerous "cookie eater" applications, some which run on a schedule or in the background, that delete cookie files for you. As with turning off cookies entirely, you may have trouble accessing sites that require certain cookies (though in most cases the worst that will happen is that you'll have to re-enter a login ID and password you thought were saved.) "Eating" the cookies periodically still permits sites to track what you're doing for a short time (i.e., the time between successive deletion of your cookie file), but thwarts attempts to discern and record your actions over time. See Real Time Cleaner.

The best solution doesn't exist yet: Full cookie management abilities built into the browsers themselves. Only increased user pressure on Microsoft, Netscape and other browser makers can make this happen. Users should ultimately be able to reject cookies on a whole-domain basis, reject all third-party cookies by default, reject all cookies that are not essential for the transaction at hand, receive notice of exactly what a cookie is intended for, and be able to set default behaviors and permissions rather than have to interact with cookies on a page-by-page basis. This just isn't possible yet. You may wish to contact the company that makes your browser software and demand these essential features in the next version.

Microsoft Windows and Microsoft Internet Explorer are registered trademarks of Microsoft Corporation, Mac is a trademark of Apple Computer, Inc., Netscape is registered trademark of Netscape Communications Corporation, JavaScript is a trademark of Sun Microsystems, Inc; special thanks to EFF's