Marc Andreessen was the co-founder and chief technical mind behind the Internet company Netscape. Andreessen was still a student researcher at the University of Illinois at Urbana-Champaign in 1993 when he helped conceive and create the first popular Internet browser, known as Mosaic. After graduation he moved to California and soon teamed with former Silicon Graphics founder James Clark to found Netscape. Andreessen was just 22 years old. The company released its first browser, Netscape Navigator, in December of 1994. Netscape held its intial public offering on 9 August 1995, and the stock jumped from an opening price of $28 to an astounding closing price of $58 on the first day. (Netscape's IPO effectively kicked off the dot-com stock boom of the late 1990s.) By the end of 1995, Andreessen was worth over $170 million and had become the very model of the ascendant techno-geek; Business Week magazine later called him a "hamburger-chomping pop icon for the cyber generation." Andreessen continued at Netscape as Chief Technical Officer (CTO) and then served as their executive vice president of products until America Online (AOL) acquired the company in 1999. Andreessen was briefly the CTO of AOL, but left later in 1999 to create Loudcloud, a web services firm. The company name was changed to Opsware in 2002, with Andreessen continuing as its chairman.

Andreessen grew up in New Lisbon, Wisconsin, where his mother worked for the clothing company Land's End.