Web beacon

Method to track the viewing of a webpage

A web beacon is a technique used on web pages and email to unobtrusively allow checking that a user has accessed some content. Web beacons are typically used by third parties to monitor the activity of users at a website for the purpose of web analytics or page tagging. They can also be used for email tracking. When implemented using JavaScript, they may be called JavaScript tags. Web beacons are unseen HTML elements that track a webpage views. Upon the user revisiting the webpage, these beacons are connected to cookies established by the server, facilitating undisclosed user tracking.

This keyword could refer to multiple things. Here are some suggestions: