What are Web Beacons (also known as Web Bugs) and Clear GIFs?
Web beacons, also called web bugs and clear GIFs are used in combination with cookies to help people running websites to understand the behaviour of their customers. A web beacon is typically a transparent graphic image (usually 1 pixel x 1 pixel) that is placed on a site or in an email.
The use of a web beacon allows the site to record the simple actions of the user opening the page that contains the beacon. The beacon is one of the ingredients of the page, just like other images and text except it is so small and clear that it is effectively invisible. Web pages and graphical emails use presentation code that tells your computer what to do when a page is opened. While they may contain some of the text that you see on the screen at the time they typically contains a number of instructions, or tags' that then ask the website's server to send you further content (such as an image or a block of text that changes frequently). Web beacons are retrieved in the same way and the action of calling the material from another server allows the event to be counted.
When a user's browser requests information from a website in this way certain simple information can also be gathered, such as: the IP address of your computer; time the material was viewed; the type of browser that retrieved the image; and the existence of cookies previously set by that server. This is information that is available to any web server you visit. Web beacons do not give any "extra" information away. They are simply a convenient way of gathering the simplest of statistics and managing cookies.
Web beacons are typically used by a third-party to monitor the activity of a site. Turning off the browser's cookies will prevent web beacons from tracking your specific activity. The web beacon may still record an anonymous visit from your IP address, but unique information will not be recorded.
For example a company owning a network of sites may use web beacons in order to count and recognise users travelling around its network. Rather than gathering statistics and managing cookies on all their servers separately, they can use web beacons to keep them all together. Being able to recognise you enables the site owner to personalise your visit and make it more user friendly.