Marc Lowell Andreessen ( ann-DREE-sən; born July 9, 1971) is an American entrepreneur, investor, and software engineer. He is the co-author of Mosaic, the first widely used web browser; co-founder of Netscape; and co-founder and general partner of Silicon Valley venture capital firm Andreessen Horowitz. He co-founded and later sold the software company Opsware to Hewlett-Packard. Andreessen is also a co-founder of Ning, a company that provides a platform for social networking websites. He sits on the board of directors of Facebook. Andreessen was one of six inductees in the World Wide Web Hall of Fame announced at the First International Conference on the World-Wide Web in 1994.