A graphical representation of data where varying degrees of a single metric are shown using colors.
Heatmaps are often used by online marketers to show what percentage of people interacted with different parts of a web page, whether it is via eyetracking, clicktracking, mousetracking, etc. The most-used parts of the page are often displayed with dark red, with less viewed parts displayed as lighter red, orange, yellow, etc. This can be a very powerful tool when preparing website navigation and sales copy.
Useit: Eyetracking Research – includes "Eyetracking Web Usability" book excerpt,related articles, plus free 159-page "Eyetracking Methodology" report
8 Heatmap Tools and Why / How to use them
KnowTeBook (August 18, 2008)