Web Privacy Tips: Understanding "Cookies"
What are Cookies?
A "cookie" is a mechanism used by a web server to both store and retrieve
information on a client machine. It is basically a block of data that is
sent to your web browser (e.g., Netscape) from a web server. Your browser
accepts this data and stores it on your hard disk. At some later time when
you revisit a site, your web browser will give the information in the
back to the server.
Cookies generally expire after a specified date. A cookie is never
as code, so there's no danger of viruses infecting your system through the
use of a cookie. But a cookie can contain whatever data the sender wants
to store about you. It could contain your IP address or a unique ID
by the server. If you provide an e-mail address or credit card number when
you visit a site, this might be stored in the cookie.
Uses for Cookies
Cookies are typically used for things like tracking visits to web sites,
site-personalization, on-line shopping carts, and web path mappings. Many
or to track the number of unique visitors or to count repeat visits from
a server that supports CGI scripts.
If you are concerned about your privacy, you can prevent cookies from being
placed on your hard drive. Most browsers, including
Navigator and Microsoft Internet Explorer, contain an option you
can set to warn you any time a server tries to send a cookie. You can then
look over a cookie's contents before accepting or denying it. However,
are so many web servers now using cookies that it can become very annoying
to accept or deny each one.
Another approach is to force your browser to refuse all cookies by making
the file where your browser stores its cookies nonreadable. Most systems
have file-locking methods that you can use to do this (check the
that came with your system).
visits. Most servers maintain logs that show your IP address and the URL
of the previous site you visited as well as where you go next.
More Information on Cookies
To learn more about cookies check out these sites:
If you want to find out what a site knows about you when you visit, check
out the CDT Privacy Demonstration at the Center for Democracy and Technology. This
site contains good information for those who are concerned about privacy.
If you want the opportunity to surf the web without revealing any personal
information, check out The
CU Web Forum