Marc Andreessen, 28
First he helped make the Internet accessible to nonprofessionals by co-creating the browsers that launched the public's stampede to get connected--Mosaic and Netscape Navigator. Then at 23,he became one of the first overnight Internet multimillionaires when Netscape, which he co-founded, made its Wall Street debut. When America Online bought Netscape in 1998, Marc Andreessen became CTO. In September, after 7 months guiding a company with as many subscribers as the combined population of Denmark and Sweden, he stepped aside. The move leaves him connected to AOL as a part-time consultant. Fittingly, this super-entrepreneur will advise the company on its investments in high-tech startups.
At 6 feet 4 inches, Andreessen exudes gawky charm, and displays a polymath's knowledge of the most exotic subjects. An Internet analyst told Fortune: "When Marc doesn't know about something he thinks he needs to understand, he gets a book and talks to people and learns. The guy has a knowledge base that is just incredible." Ultimately, his greatest influence on the future of technology could be the outcome of the Justice Department's antitrust suit against Microsoft, in large part the result of Bill Gates' business practices vis-à-vis Andreessen's Netscape.