US software developer and businessman. While still an undergraduate at the University of Illinois, he led the team that developed the Mosaic web browser (1992–93). In 1994 he co-founded Mosaic Communications, later Netscape Communications Corporation, which in the same year released Netscape Navigator. Andreessen left Netscape following its acquisition by AOL in 1999. He has subsequently founded two further companies, Loudcloud (now Opsware, Inc.) and Ning.