According to Google help page, "Trends for Websites combines information from a variety of sources, such as aggregated Google search data, aggregated opt-in anonymous Google Analytics data, opt-in consumer panel data, and other third-party market research…. Additionally, Google Trends for Websites only shows results for sites that receive a significant amount of traffic, and enforces minimum thresholds for inclusion in the tool."

Google says, “Google Trends is a Google Labs product, which means it's still in its early stages of development. The data Trends produces may contain inaccuracies for a number of reasons, including data-sampling issues and a variety of approximations that are used to compute results. We hope you find this service interesting and entertaining, but you probably wouldn't want to write your Ph.D. dissertation based on the information provided by Trends.”

Currently Google doesn’t give out information on itself on its "Google Trends For Websites" website.

Google states, "We have policy of not providing interim financial guidance, and have decided not to release Google numbers in accordance with that policy."

Google Trend for Websites is found at: http://www.google.com/trends