Cookie. You wouldn't think a computer tool with such a playful-sounding name would create the fear that it does. But these tiny Web-browser helpers are an example of how the useful can get tossed in with the dangerous through the hysteria brought about by the real threats of computer viruses, hacking, spyware, spam, and phishing.

In the past, Congress has considered anti-spyware legislation that has the potential of banning cookies that you don't specifically agree to allow a Web site to place on your computer's hard disk. (Congress likely will consider it in the future as well.) At first glance, this legislation seems like a good idea. But it would hurt the online advertising industry, and, for consumers, it would likely mean that there would be fewer free Web sites and more pay sites.

So, what exactly are cookies, and are they really worth getting worked up over?

A cookie is a small data file that can serve any number of purposes. It can prevent you from having to type in your user name and password each time you visit a site that requires a login. It can keep track of your preferences with those sites that allow you to specify the type of content you want to see or how you want to see it. It can be used by e-commerce security systems to identify your browser as protection against hackers. And it can be a way for Web sites and their advertisers to track where people click so they can better target their content and advertising.

It's the tracking that most worries some people, who feel that it allows Big Brother to peer over their shoulder and watch them as they surf. But the first purpose, storing user names and passwords, is more of a threat. Both threats, though, are overblown.

The big concern is third-party cookies, which are set not by the site you're at, but rather by Web banner advertising companies such as DoubleClick.

Keep in mind, though, that cookies aren't spyware. Advertisers and the companies that service them use cookies to track aggregate behavior and to customize ads. This prevents you, for instance, from seeing the same ad over and over at different sites. They don't link what you do on the Web to who you are.

One potential problem with cookies, though, is the theft of the user name and password information in them by hackers who could then access your bank, credit card, or other account. The solution, as with other hacking threats, is to use a firewall program to protect this and other sensitive data on your computer.

The core issue is who pays for Web content. Just as with other media, if you diminish ad revenue, the money has to come from somewhere else. In this case, that means you.

If Congress passes anti-spyware legislation that bans cookies you don't specifically agree to accept, you would need to click on an “OK” dialog box, agreeing to accept cookies, multiple times, page after page, as you surf any given Web site. This obviously would render cookie technology unwieldy and would require an alternative technology, which could take a year or longer to develop, said Dave Morgan, CEO of TACODA Systems, Inc. (http://www.tacoda.com), an online advertising services firm in New York City that helps large publishers target their online ads.

In the meantime, some sites would likely switch to subscriptions for the bulk of their content rather than keep it free.

If you're still concerned with cookies (and many people are), you have options. Web browsers let you disable third-party (or all) cookies or otherwise customize how you deal with cookies when you surf. Internet Explorer saves cookies in separate files in the Cookies folder. Netscape saves cookies in a single file called cookies.txt.

The Web site GetNetWise (http://privacy.getnetwise.org/browsing/tools) provides instructions on how to change your browser's settings to customize how it manages cookies, whether you use Internet Explorer 6 or 5; AOL 8, 7, 6, or 5; Netscape Navigator 7, 6, or 4.5; or Opera 6 or 5. Disabling all cookies, however, can limit your experience with some sites and can prevent you from accessing others.

DoubleClick (http://www.doubleclick.com/us/about_doubleclick/privacy/ad-cookie) gives you the option of opting out of its site-to-site cookie tracking, as does the Network Advertising Initiative (http://www.networkadvertising.org) for DoubleClick as well as similar online advertising services.

The personal computer revolution is all about personal choice, and this includes cookies.