text: Web beacons (sometimes called "transparent GIFs," "clear GIFs," or "pixel tags") are small strings of code that embed a small graphic image (usually invisible) on a web page or in an email or advertisement. When your browser downloads a web beacon, the server that sends the corresponding image to your browser can recognize and store certain types of information such as cookies previously set, the time and date that you viewed the page embedded with the beacon and a description of that page.