Eye tracking is a process that measures where a person is looking. It is used in fields like psychology and product design. There are different eye tracking methods, including contact lenses and optical tracking techniques. Eye tracking is used in marketing to test advertisements and product designs by observing what users look at. A case study examined the "Google gold triangle" theory that users' eyes are drawn to the top and left results in search engine results pages. Eye tracking tests on hotel searches supported the theory, showing users primarily clicked on promoted ads and top maps results. The conclusion was the Google gold triangle remains valid for businesses wanting top search placement or ad clicks.