Also called a Web bug or a clear GIF. Used in
combination with cookies, a Web beacon is an often-transparent
graphic image, usually no larger than 1 pixel x 1 pixel, that
is placed on a Web site or in an e-mail that is used to monitor
the behavior of the user visiting the Web site or sending
the e-mail. When the HTML code for the Web beacon points to
a site to retrieve the image, at the same time it can pass
along information such as the IP address of the computer that
retrieved the image, the time the Web beacon was viewed and
for how long, the type of browser that retrieved the image
and previously set cookie values.
Web beacons are typically used by a third-party to monitor
the activity of a site. A Web beacon can be detected by viewing
the source code of a Web page and looking for any IMG tags
that load from a different server than the rest of the site.
Turning off the browser's cookies will prevent Web beacons
from tracking the user's activity. The Web beacon will still
account for an anonymous visit, but the user's unique information
will not be recorded.
