Tracking pixel · WebGlossary.info · Uncover Your Unknowns in Web Development

One of various techniques used on web pages and email to unobtrusively (usually invisibly) allow for checking that a user has accessed some content. Tracking pixels are typically used by third parties to monitor the activity of users of a website for the purpose of web analytics or page tagging. They can also be used for email tracking. Using such pixels, companies and organizations can track the online behavior of web users. At first, the companies doing such tracking were mainly advertisers and web analytics companies; later social media sites also started to use the same tracking techniques, for instance through the use of buttons which act as tracking beacons. ← Wikipedia