Cookies are one of the most widely used,
misused, and misunderstood features of the Web. Their basic function is
simple: allow Web servers to store and retrieve information on the
client-side. Although cookies can make the Web surfing experience more
personalized and streamlined, many users regard them with suspicion
because of concerns about privacy.
When used correctly, cookies can be a very useful
tool. They are used to simplify sign-on procedures, set up shopping
carts, and provide individual users with more personalized information
on a web site. Internet users are becoming increasingly discriminating:
they demand useful content presented quickly and clearly.
What Cookies Are - And Are NOT
First, you must understand what cookies are:
- A cookie is a unique small bit of information sent by a
Web server to identify a particular computer and browser.
- Cookies are stored in a text file whose exact name and
location depend on your operating system and browser.
- Cookies can contain specific information about the user:
- Username and password
- Date of last visit
- Web servers use the stored information to identify the
particular user by requesting validation information from
- Cookies are browser-specific. A cookie set when you
browse in Netscape Navigator will not be read if you visit
the same site again using Internet Explorer.
Even more important, understand what cookies are NOT:
- Cookies cannot store any of your personal information
that you don't voluntarily supply to the Web site.
- Cookies do not contain viruses.
- A server can only get data from the cookie it wrote to
the cookie file - it can't go fishing for information in your
A good example of a simple cookie is on the
Amazon.com Web site. Registered users see a personalized message when
"Hello, John Smith, we have recommendations for
you in books, music, and video."
The links will take you to a personalized page that
highlights products based on your personal profile.
Useful Applications For Cookies
reasons. Some of the most common include:
Site Personalization - As in the Amazon
example above, a cookie is used to identify you and direct
you to areas of the site that might interest you most.
This can be as simple as flagging new stories or
products added to the site since your last visit or as complicated as
rendering pages that are almost completely customized based on stored
preferences (favorite music, nonfiction categories, etc).
Online Ordering - Many e-commerce sites use
cookies to track additions or deletions to your shopping cart. Sites can
use session cookies that are valid only for the duration of that
particular visit, or design them so that you can return to the site days
later and complete your transaction.
Web site Tracking - Cookies provide a more
accurate count of site visitors. Using cookies, can insure that someone
who visits a web site 3 times per day isn't counted as a unique user
each time. It can also see how often repeat visitors visit and what
items they view most often (very helpful to personalize a site).