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[ 10-06-2000 ]
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Cookies: Unofficial FAQ

Version 2.53

Contributed to Cookie Central by David Whalen

What's new in this release

Complete reorganization of the FAQ. Added 2 new Sections:

General Questions/Miscellaneous

and

Advanced Topics

. All new topics are indicated below.

A Note from the Author

1. INTRODUCTION

A Note from the Author

(Version 2.5)

Well, well. A major update! Thanks for all your questions. I've tried to integrate them into the update as best as possible.

The FAQ has definitely gotten some attention lately! I have been interviewed 3 times, and the FAQ has been quoted a dozen or so times in articles on and off the Web. Not a bad little reception! I'm concerned that some people have chosen to quote the FAQ directly without my written permission. While I have no intention of getting in the way of spreading knowledge, I must insist that I be told when people intend to use my work. If you can't handle asking for permission, then don't use the FAQ in your works. If you're confused, feel free to read the

Important Disclaimer and Copyright Information

again.

Finally, thanks for all your kind letters and feedback. It helps remind me why I do the FAQ in the first place.

Thanks for stopping by!

-- DW

1. INTRODUCTION

Cookies are a very useful tool in maintaining state variables on the Web. Since HTTP is a "stateless" (non-persistent) protocol, it is impossible to differentiate between visits to a web site, unless the server can somehow "mark" a visitor. This is done by storing a piece of information in the visitor's browser.

This is accomplished with cookies. Cookies can store database information, custom page settings, or just about anything that would make a site individual and customizable. An analogy I like to use is that cookies are very much like a laundry "claim-check" of sorts. You drop something off, and get a ticket. When you return with the ticket, you get that same something back.

1.1 What is a Cookie?

A cookie is simply an HTTP header that consists of a text-only string that gets entered into the memory of a browser. This string contains the domain, path, lifetime, and value of a variable that a website sets. If the lifetime of this variable is longer than the time the user spends at that site, then this string is saved to file for future reference.

1.2 Where did the term cookies come from?

According to an article written by Paul Bonner for

Builder.Com

on 11/18/1997:

"Lou Montulli, currently the protocols manager in Netscape's client product division, wrote the cookies specification for

Navigator

1.0, the first browser to use the technology. Montulli says there's nothing particularly amusing about the origin of the name: 'A cookie is a well-known computer science term that is used when describing an opaque piece of data held by an intermediary. The term fits the usage precisely; it's just not a well-known term outside of computer science circles.'"

1.3 Why do sites use Cookies?

There are many reasons a given site would wish to use cookies. These range from the ability to personalize information (like on My Yahoo or Excite), or to help with on-line sales/services (like on Amazon Books or Microsoft), or simply for the purposes of tracking popular links or demographics (like DoubleClick). Cookies also provide programmers with a quick and convenient means of keeping site content fresh and relevant to the user's interests. The newest servers use cookies to help with back-end interaction as well, which can improve the utility of a site by being able to securely store any personal data that the user has shared with a site.

1.4 Where Can I Get More Information?

Cookie Central

is dedicated to answering questions about cookies. If you can't find your answers there, one may not exist.

The World Wide Web Consortium has an excellent FAQ to answer the majority of Internet and Web-related questions. You can read their topic:

"Do 'Cookies' Pose any Security Risks?"

In addition, there are an abundance of resources on the Internet that can help you find answers to your cookie questions. Conveniently,

Yahoo

has a great listing of them. I encourage you to stop by and check the list out!

If you like having an actual paper book by your side, I strongly encourage Simon St. Laurent's

cookies

, published by Computing McGraw Hill. You can

find it on Amazon.com

, or try your local bookstore!

]

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HTTP Cookies

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