OK, So what is a Cookie?

Basically, a Cookie, or 'Persistent State Client-Side Variable' as it is formally known, is a 'nugget' of information which a Web-Page can send to your browser for it to store away for future use.

Each Cookie 'belongs' to a Web-Site and will be sent back to its originating Web-Site each time you request a page from it.

Each Cookie has an expiry date, some Cookies expire when you end your browser session (e.g. terminate the program), however the majority have an expiry date set into the future for re-use on subsequent sessions.

J.Pe@s' Personal Navigator has set a Cookie (JPPNLAST) with the Day of the Year on which you last visited it. This way, it can greet you suitably each time you return!

Who else uses Cookies?

Many sites which allow on-line shopping use the Cookies to store your selections away, that way if you return to the store, it remembers your selections!
e.g. The Netscape Store

Infoseek Guide uses Cookies to remember how you like your screen arranged.

Hotwired and FireFly both store your UserName and Password as Cookies, to save you having to re-enter them on each visit!

This is no more risky than typing them into the usual requester and, additionally, many sites support secure Cookies, transferred using SHTTP or SSL.

Microsoft and Netscape both offer 'customisable' Home Pages, which store your preferences as Cookies!

OK, how do I use Cookies?

Well, I suggest reading the following (excellent) references on the topic, they are how I found out about Cookies in the first place.

• Netscapes' "Preliminary Specification" on Persistant Client-State HTTP Cookies
• How do they do that in HTML? has a better explanation of Cookies than mine
• Andys' Netscape Cookie Notes has some source code and further links