Baidu??, Inc. (, pronounced BY-doo in English), incorporated on January 18, 2000, is a Chinese web services company headquartered in the Baidu Campus in Haidian District in Beijing. Baidu offers many services, including a Chinese language-search engine for websites, audio files, and images. Baidu offers 57 search and community services including Baidu Baike (an online collaboratively built encyclopedia) and a searchable, keyword-based discussion forum. Baidu was established in 2000 by Robin Li and Eric Xu. Both of the co-founders are Chinese nationals who studied and worked overseas before returning to China. , Baidu ranked 5th overall in the Alexa Internet rankings. During Q4 of 2010, it is estimated that there were 4.02 billion search queries in China of which Baidu had a market share of 56.6%. China’s Internet-search revenue share in second quarter 2011 by Baidu is 76%. In December 2007, Baidu became the first Chinese company to be included in the NASDAQ-100 index. In December 2014, Baidu was expected to invest in the company Uber. Baidu provides an index of over 740 million web pages, 80 million images, and 10 million multimedia files. Baidu offers multimedia content including MP3 music, and movies, and is the first in China to offer Wireless Application Protocol (WAP) and personal digital assistant (PDA)-based mobile search. Baidu Baike is similar to Wikipedia as an encyclopedia; however, unlike Wikipedia, only registered users can edit the articles due to Chinese laws. While access to Wikipedia has been intermittently blocked or certain articles filtered in China since June 2004, there is some controversy about the degree to which Baidu cooperates with Chinese government censorship.