An interesting question came up recently from one of clients, what?'s the difference between Heat Maps and Click Overlays as they relate to SEO? It turns out that there isn?t a simple answer to the question and there?'s plenty of confusion and misunderstanding surrounding their use. For instance, Google has Heat Maps?...false?...Google has Click Overlays that they call Site Overlays. Heat Maps are generated from eye-tracking studies?...sometimes true?...Heat maps and Eye Tracking Studies can look the same but are completely different in that one measures clicks and the other tracks eye movements through biometric devices.

However, the goal and purpose of the Heat Map versus Click Overlay are the same.  Track human activity on your web page.  In the case of Heat Maps, view or click densities are displayed like thermal heat images with red, yellow, green and blue, red being the hottest areas and blue being the least viewed or clicked.

 
Click Overlays usually show click activity in terms of numbers and percentages that can also be tied to other relevant factors such as keywords, goals and revenue.  One of the first things you will notice about Click Overlays is that numbers and percentages don?t seem to add up to the total clicks or 100%.  There?s good reason for this because Click Overlays track clicks in terms of URLS, so that if you have links on your page that point to the same place or page then those clicks get associated with ALL links on that page for that URL.  Also, Site Overlays are not going able to measure clicks on links that use javascript, redirects, external links, redirects or subdomains.