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. In March 2015, Baidu ranked 4th overall in the Alexa Internet rankings.