The Netscape Unofficial FAQ

What are Cookies?

Applies to: Navigator and Communicator(all versions)
Operating Systems: MacOS, UNIX, Windows 3.x, Windows95, and Windows NT



We see many questions and comments about "cookies".

This brief paper provides a somewhat simplified explanation of what cookies are all about. The official definition of "cookies" (from Netscape- who designed this use of "cookies") can be found at the site noted at the bottom.

"Cookies.txt", or something similar, is the name of a file which holds some information about your machine and, IF you give it out, about you.

Many people think "cookies" are sinister way to gather information about you. As you will see there is nothing sinister going on. Of course if you are paranoid the preceeding statement "proves" cookies are sinister, in which case you have my sympathy, but the facts are otherwise.

To understand what cookies are all about and why they exist, let us start with the fact that a large Website might be visited by, literally, a million different people, or more over the course of a year. It is often to the advantage of both the visitors and the people running the site,to know something about the visitor when they get to the site.

Of course many people visit a site just once, or very infrequently so storing information about visitors to a site can be both wasteful and expensive (and looking it up can be very slow). The cookies.txt file concept was invented to allow information about visitors to be available to sites the visitor goes to.

The cookies.txt file is a small text file in the base Netscape directory. No single entry can be more than 4000 bytes long and there cannot be more than 300 entries in the whole file, nor more than 20 entries per "site", (there are other rules too). Most importantly, no one can TAKE information FROM your cookies.txt file. That's not the way it works.

Information is put INTO your file by a site. A site can put a very limited amount of information into your file UNLESS you answer some questions somewhere on that site. All a site can know about you basically, is that you visited them, when, and which pages on that site you went to look at. If you answer a questionnaire, it is possible for a site to record on your disk some more information about you - but only what you have been willing to tell.

The way a site GETS information from you is when you tell Netscape to go to a site, Netscape looks in the cookies.txt file and if the URL (address) matches the site you are going to, then Netscape will SEND the informationin your cookies.txt file, for that URL only. To repeat: A site cannot ASK for information from your cookies.txt file. It is SENT information when you go and it's sent the information only if you've been there before.

Furthermore, the information in the cookies.txt file expires depending upon what the site sets for an expiration date / time and if there is no expiration date and time, information expires very quickly (many sites do not bother setting dates and times).

This is where you will find the official definition:

This is a direct quote from the official definition:


"A server, when returning an HTTP object to a client, may also send a piece of state information which the client will store. Included in that state object is a description of the range of URLs for which that state is valid. Any future HTTP requests made by the client which fall in that range will include a transmittal of the current value of the state object from the client back to the server. The state object is called a cookie, for no compelling reason.

This simple mechanism provides a powerful new tool which enables a host of new types of applications to be written for web-based environments. Shopping applications can now store information about the currently selected items, for fee services can send back registration information and free the client from retyping a user-id on next connection, sites can store per-user preferences on the client, and have the client supply those preferences every time that site is connected to."

Now you see why we wrote the stuff above:-))

For more on Cookies ....

See the PC Magazine Article April 22 Issue

- Broken Links? - Legal Info

For Information On More Communicator Custom Preferences, See: Advanced Communicator Preferences