Watching for Web Bugs

A "Web bug" is a small object on a Web page whose purpose is to collect information. The term typically refers to a 1-pixel-by-1-pixel GIF image from a third party. Like any other object you download as part of a Web-page request, Web bug servers receive the basic data from your browser—your IP address, the page you linked from, your ISP, and so on. (See What Your Browser Gives Away.) Like all other third-party objects, they can also transmit and replay cookies associated with the underlying site.

Web bugs disturb many computer users because of their stealthy nature. A 1-by-1 image is an unnoticeable speck on your screen, but its eyes and ears are as large as those of the tallest skyscraper ad. Knowing that Web bugs exist, ...

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