An eye tracker is a tool that records and evaluates a person's eye movements, allowing us to understand where they are looking, what they are paying attention to and, conversely, what stimuli they are ignoring. It works using a system that exploits light with a frequency close to infrared. This frequency band is below our perception threshold, so we cannot see it with the naked eye, but when it is directed towards the eyes, it generates a physiological reflection of the cornea that is visible.
