Biography

Co-creator of Mosaic (1993), the first mainstream web browser, and then co-founder of Netscape, Marc Andreessen revolutionized access to the Internet. He went on to become one of Silicon Valley's most influential investors, co-founding the venture capital firm Andreessen Horowitz.

Marc Andreessen(1971 — ?)

Marc Andreessen

États-Unis

9 min read

TechnologyEconomicsEntrepreneur(e)21st CenturyThe Digital Age and the Internet Revolution

Frequently asked questions

Marc Andreessen is an American computer scientist and investor born in 1971, who became famous for co-creating Mosaic in 1993, the first mainstream graphical web browser. The key takeaway is that with Mosaic, he transformed the Internet — until then reserved for researchers — into a tool accessible to everyone by displaying images and text on the same page. He went on to co-found Netscape in 1994, whose browser captured more than 80% of global internet users by 1995, before becoming an influential investor through the Andreessen Horowitz (a16z) fund.

Key Facts

  • 1993: co-develops Mosaic, the first graphical web browser for general audiences, at the University of Illinois
  • 1994: co-founds Netscape Communications Corporation
  • 1995: Netscape's IPO, a defining symbol of the start of the dot-com boom
  • 1998: Netscape is acquired by AOL for $4.2 billion
  • 2009: co-founds the venture capital firm Andreessen Horowitz (a16z), which becomes one of the most powerful in Silicon Valley

Works & Achievements

Mosaic (1993)

The first mainstream graphical web browser, developed at NCSA. For the first time, it allowed images and text to be displayed on the same web page, making the Internet accessible to non-specialists and triggering worldwide adoption.

Netscape Navigator (1994)

A commercial browser co-founded with Jim Clark and distributed free of charge to individuals. At its peak in 1995, it was used by more than 80% of internet users worldwide, before being overtaken by Internet Explorer.

Netscape IPO (August 9, 1995)

A defining moment of the dot-com boom: Netscape went public without having turned a profit, yet saw its stock price double on the first day. The offering marked the entry of institutional investors into the digital economy.

Loudcloud / Opsware (1999–2007)

A cloud computing company founded well ahead of its time, eventually sold to HP for $1.6 billion in 2007. This entrepreneurial adventure shaped the investment thesis that Andreessen and Horowitz would later bring to venture capital.

Andreessen Horowitz (a16z) (2009)

A venture capital firm co-founded with Ben Horowitz. With more than $35 billion under management in 2024, it is one of the most influential funds in the world, having backed Airbnb, GitHub, Slack, Lyft, and hundreds of other startups.

'Why Software Is Eating the World' (2011)

An essay published in the Wall Street Journal that became a landmark text in technology thinking. Andreessen predicted that software companies would come to dominate every sector of the economy — a prophecy that has since been largely borne out.

Anecdotes

When Marc Andreessen developed Mosaic at the University of Illinois in 1993, he was a simple student employed at NCSA for $6.85 an hour. Within a few months, his browser had been downloaded millions of times and radically transformed how people used the Internet — which until then had been the exclusive domain of researchers and the military. Nobody, not even his supervisors, had anticipated such widespread adoption.

In August 1995, Netscape went public without having turned a single dollar of profit. The stock price doubled on the first day, valuing the company at more than two billion dollars. Andreessen, aged 24, became a millionaire overnight — the IPO is considered the unofficial starting gun of the dot-com bubble.

The February 1996 cover of *Time* magazine showed Andreessen sitting barefoot on a golden throne. The image became an icon of the dot-com era, symbolizing both the triumph of a generation of young engineers and the hubris of a Silicon Valley that believed itself invincible.

In 1995, Bill Gates wrote an internal memo titled "The Internet Tidal Wave

in which he identified Netscape as the primary threat to Microsoft. He mobilized the entire company to develop Internet Explorer and bundle it free with Windows — a strategy that would lead to a landmark antitrust lawsuit against Microsoft.

In 2011, Andreessen published an essay in the *Wall Street Journal* titled "Why Software Is Eating the World

predicting that almost every sector of the economy would eventually be dominated by technology companies. The article has since been cited as one of the founding texts of contemporary entrepreneurial thinking.

Primary Sources

Bill Gates internal memo: 'The Internet Tidal Wave' (May 26, 1995)
I want to get your thoughts on something I consider the most important development since the IBM PC in 1981. The Internet is becoming unavoidable [...]. Netscape has created a very popular browser and represents our greatest threat.
Netscape Communications Corporation IPO Prospectus (August 1995)
Netscape offers client and server software for browsing and publishing on the World Wide Web. The company has distributed more than six million copies of its Netscape Navigator software since December 1994.
Marc Andreessen, 'Why Software Is Eating the World', Wall Street Journal (August 20, 2011)
Software companies are poised to take over large swaths of the economy. [...] In the next ten years, I expect many more industries to be disrupted by software, with new technology players dominating retail, healthcare, education, and financial services.
Marc Andreessen interview in Playboy Magazine (1994)
We created Mosaic because information existed on the network but nobody could access it easily. We wanted to make the Internet available to everyone, not just scientists.
Official announcement of the founding of Andreessen Horowitz (a16z) (July 2009)
Andreessen Horowitz is a $300 million venture capital fund dedicated to early-stage and growth-stage technology companies. We believe software will continue to fundamentally transform every sector of the global economy.

Key Places

Cedar Falls, Iowa, United States

Marc Andreessen's hometown, where he was born in 1971. This Midwestern city, far from any tech hub, illustrates the journey of an ordinary family's son who became a global figure in technology.

NCSA, University of Illinois at Urbana-Champaign

It was in the facilities of the National Center for Supercomputing Applications that Andreessen developed Mosaic in 1993. This university campus thus became the birthplace of the mainstream Web.

Mountain View, California (Netscape headquarters)

Silicon Valley. Netscape set up there in 1994; its offices became a symbol of the Internet frenzy of the 1990s, drawing engineers from around the world and investors ready to bet millions on companies with no profits.

Menlo Park, California (Andreessen Horowitz headquarters)

Located on Sand Hill Road, the nerve center of global venture capital, the a16z office embodies Andreessen's new role: no longer a product builder, but a financier and mentor to the entrepreneurs reshaping the world.

New York Stock Exchange, New York

The symbolic site of Netscape's IPO in August 1995, a founding moment of the dot-com bubble. The stock's dramatic surge on its first day of trading marked the beginning of an era of unprecedented speculation around technology stocks.

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See also