This excerpt taken from the SOHU 10-K filed Mar 25, 2005.
In 2004, we launched our new search engine: www.sogou.com. The new search engine performs a pioneering interactive search through a built-in algorithm that combines the results generated from the hundreds of thousands of manually selected high-quality Websites in Sohus directory with hundreds of millions of pages that the engine searched from the World Wide Web. The user is taken through a fast and convenient interactive process to arrive at the most relevant selection of the integrated Website and page search results. On February 25, 2005, we launched our upgraded search engine Sogou 2.0 with an expanded breadth of 500 million Chinese language indexed web pages, higher updating speed and shorter search time.