Google Trends is a tool from Google Labs that shows the most popularly searched terms based on one or more keywords from the beginning of 2004 to now. Google Trends charts how often a particular search term is entered relative the total search volume across various regions of the world, and in various languages.
With Google Trends, you can compare the world’s interest in your favorite topics. Enter up to five topics and see how often they’ve been searched on Google over time. Google Trends also shows how frequently your topics have appeared in Google News stories, and in which geographic regions people have searched for them most.
This is an excellent tool to add to your SEO arsenal.