Accepting Cookies Can Be Good for You

A "cookie" is a piece of information created by a Web server and sent to your Web browser to be stored on your computer. When you revisit the Web server that gave you the cookie, your browser sends that cookie back to the server. The Web server now recognizes that you have visited before, and can present customized pages to you based on information stored in the cookie.

How Are Cookies Used?

Cookies are a useful tool for applications, or services, on the Web. They provide a way of saving information--called saving "state"--that can be used later by the Web application. This allows you to continue from where you left off the last time you used a particular Web service. If you were shopping for books at Amazon.com, for example, you could come back later to finish selecting the ones you want.

Cookies can also help identify who you are so that you do not have to re-enter basic information such as login name and password each time you visit a Web site. Several UW Web-based applications will use cookies in this way.

Cookies often contain your profile or identifying information that can be looked up by the application in the server's database. A profile can contain a variety of information that is useful if you visit a Web server more than once.

The following are examples of Web applications that use cookies to accomplish a task or provide a service:

Information-providing applications such as the New York Times Web site can store which categories of information are of interest to you. You may want to know about international news, weather, and gardening, for example, but not sports or fashion news.
Online shopping applications can store items you have selected to purchase in your "shopping cart." If you get called away, you can return later to continue your shopping and purchase all the items in your cart at once.
Marketing applications can keep track of the types of advertisements you click on so that you are shown more ads in similar categories, or so you are not shown the same one twice.

What About My Privacy?

You may have heard that cookies are a threat to your privacy. The people providing Web services that distribute cookies are generally trying to improve customer service rather than invade your privacy. A cookie cannot seek out data from your hard drive or steal sensitive information about yourself.

Information about your computer and browser and what Web pages you visit is already available, without using cookies, in a Web server's log files, and could also be used to track your browsing habits. Cookies just provide a convenient way to package the information for use by a particular Web application.

You may be wondering--could a cookie contain my email address? It could, but only if you provided your email address to the Web server.

What Control Do I Have Over My Cookies?

[Graphic: Web
screen of a cookie warning message.]

Web sites such as Amazon.com use cookies to keep track of items in your shopping cart. If you edit your browser's preferences to warn you before accepting a cookie, you will see a request--usually multiple requests--like this.

Most Web browsers--including recent versions of Internet Explorer, Netscape Navigator, and Lynx--support cookies. By default, they accept all cookies without warning. You do have other options you can try if you want to see what works best for you. The Web sites listed below tell you where to find your graphical browser's cookie control options.

You may find it a nuisance to be regularly asked if you want to accept a cookie (see cookie message screen). As more and more Web sites are using cookies, you may have to choose between accepting all cookies or not accepting any. And if you decide not to accept any cookies, then some Web applications--including new Web-based administrative applications at the UW--may not work as well for you.

Where Can I Find Out More About Cookies?

Information about cookies is available at many Web sites. Here are a few with more detailed information:

Cookie Central (www.cookiecentral.com/) where you will find "The Unofficial Cookie FAQ" (www.cookiecentral.com/unofficial_cookie_faq.htm)

A Microsoft site entitled "Cookies: What They Are, Why You Are In Charge" (www.microsoft.com/info/cookies.htm)

A Netscape site called "Cookies: What They Are and How They Work" (help.netscape.com/kb/client/970226-2.html)

The U.S. Department of Energy Computer Incident Advisory Capability (CIAC) Information Bulletin of March 12, 1998 on "Internet Cookies" (www.ciac.org/ciac/bulletins/i-034.shtml)

University of Washington Computing & Communications
Windows on Computing, No. 22, Winter 1999
newsltr@cac.washington.edu