Marc Andreessen, the leader of the team that developed Mosaic, left NCSA and, with James H. Clark, one of the founders of Silicon Graphics, Inc. (SGI), and four other former students and staff of the University of Illinois, started Mosaic Communications Corporation. Mosaic Communications eventually became Netscape Communications Corporation, producing Netscape Navigator. Mosaic's popularity as a separate browser began to decrease after the 1994 release of Netscape Navigator the relevance of which was noted in "The HTML Sourcebook: The Complete Guide to HTML": "Netscape Communications has designed an all-new WWW browser Netscape, that has significant enhancements over the original Mosaic program."