The Google Traffic Estimator keyword tool is a tool that Google uses to display how many search enquiries have been made on a month by month basis for a particular search term (keyword or keyword phrase). Strictly speaking it is not a traffic estimator as it actually presents data collected from the previous month based on actual enquiries put into the search engine. It is fairly clear though that by using actual data collected on a month by month basis you can in fact make reasonable assumptions as to the popularity of particular keyword or keyword phrase and then of course use that data as a traffic estimator.
