When a user opens the page or email where such an image is embedded, they might not see the image, but their web browser or email reader automatically downloads the image, requiring the user's computer to send a request to the host company's server, where the source image is stored. The image could be as small as a single pixel (thus the name “tracking pixel”) and could be of the same colour as the background, or completely transparent. The first web beacons were small digital image files that were embedded in a web page or email. They can also be used to see if an email was read or forwarded or if a web page was copied to another website. A web beacon is any of several techniques used to track who is visiting a web page.
