Baiduis the leading Chinese search engine for websites, audio files, and images. Baidu offers 57 search and community services including an online collaboratively-built encyclopedia (Baidu Baike), and a searchable keyword-based discussion forum. As of 21 March 2008, Baidu is ranked 19th overall in Alexa's internet rankings. In December 2007 Baidu became the first Chinese company to be included in the NASDAQ-100 index.