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Mosaic: The Browser That Made the Web Mainstream

Abstract

When Tim Berners-Lee invented the World Wide Web in 1990, almost no one used it. The web existed for nearly three years as a niche tool for physicists, with a handful of clunky, text-only or platform-specific browsers. Then, in 1993, a small team at a U.S. supercomputing center released NCSA Mosaic, the browser that displayed images and text on the same page, ran on the computers ordinary people owned, and installed in minutes. Between June 1993 and December 1994 the number of websites grew from about 130 to more than 10,000. Mosaic didn’t invent the web. It made the web visible, and then, having ignited the revolution, it was swept aside by the company its own creators founded.

The Web Before Mosaic: Invented but Invisible

By 1992 the World Wide Web had existed for two years. Berners-Lee had written the protocols (HTTP), the markup (HTML), and the addressing scheme (URLs), and had even written the first browser at CERN. But adoption was minuscule. The existing browsers were a fragmented lot: Berners-Lee’s original ran only on the expensive NeXT workstation; a “line-mode browser” showed text on dumb terminals; others were tied to specific Unix systems. Crucially, none of them showed images inline. The web was, in practice, walls of blue hypertext links, and it was competing for attention with rivals like Gopher, which for a time was more popular.

The web had everything it needed to succeed except a reason for ordinary people to look at it.

NCSA, Illinois, 1993

The reason came from an unlikely place: the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign, a federally funded center built around massive scientific computers. There, a young undergraduate employee named Marc Andreessen, working with a talented staff programmer named Eric Bina, decided to build a better web browser.

They released NCSA Mosaic in 1993 (NCSA X Mosaic 0.5 on 23 January, to which Tim Berners-Lee replied two days later with “Brilliant!”, the influential 1.0 in the spring, and versions for Windows and Mac by the autumn). It did several things no browser had combined before:

  • Inline images. Mosaic’s <IMG> tag let pictures appear within the page, alongside the text, rather than as separate downloads. This single decision transformed the web from a document-retrieval system into a visual medium, and was controversial, since Berners-Lee and others worried it strayed from the web’s text-centric, structured-document ideals.
  • It ran on the computers people actually had. Versions for Microsoft Windows and the Apple Macintosh (not just Unix workstations) meant that for the first time, the web was reachable from an ordinary home or office PC.
  • One-click installation and a friendly interface. Point-and-click navigation, a graphical interface, a clickable “back” model: Mosaic made browsing feel obvious to people who had never used the internet.

Mosaic Did Not Invent Inline Images, but It Won the Argument

Other early browsers (notably ViolaWWW and Erwise on Unix) experimented with graphics, and the <IMG> tag’s design was debated on the www-talk mailing list. What Mosaic did was ship inline images to a mass platform and make them the norm. The web’s evolution from austere academic hypertext into a rich visual medium (for better and worse) dates from this choice.

The Explosion

The effect was immediate and exponential. In 1992 there were fewer than a hundred web servers in the world. Matthew Gray’s Wanderer crawler counted 130 sites in June 1993, 623 in December 1993 and 10,022 in December 1994; through the second half of 1993 the web doubled in less than three months. By mid-1994 NCSA was counting 50,000 Mosaic downloads a month. Newspapers and magazines, for the first time, wrote about “surfing the internet” as something a regular person might do. Mosaic is the moment the web crossed from a research tool into a mass medium, the hinge on which the entire internet economy turns.

The web’s open, ungated nature amplified the effect: because CERN had placed the web in the public domain and Mosaic was free to download, there was nothing standing between a curious person and the global hypertext system.

From Mosaic to Netscape

Mosaic’s success created a problem: it belonged to the University of Illinois, not to the people who built it. NCSA, recognizing what it had, moved to commercialize and control Mosaic, and tensions rose with the young programmers who felt they had done the work.

In 1994, Marc Andreessen left Illinois, met the veteran Silicon Valley entrepreneur Jim Clark (founder of Silicon Graphics), and the two founded a company to build a better browser from scratch, explicitly not using NCSA’s code, to avoid the licensing entanglement. Clark, who had left SGI, invited Andreessen in January 1994, and they founded the company in Mountain View on 4 April 1994; at first they considered an online games network with Nintendo. It was first called Mosaic Communications, then renamed Netscape after a dispute with the university; the beta of Mosaic Netscape 0.9 appeared on 13 October 1994 and Netscape Navigator 1.0 on 15 December 1994, internally codenamed “Mozilla”: “Mosaic killer.” It was faster, more capable, and rapidly took the market Mosaic had created. Netscape’s initial public offering on 9 August 1995 started two hours late; the $28 shares touched $75 and closed at $58.25, valuing a company without profits at $2.9 billion and making Andreessen $59 million and Clark $566 million richer. In February 1996 Andreessen sat barefoot on the cover of Time. The full story of the company and the war it triggered is told in Marc Andreessen and Netscape and The Browser Wars.

Meanwhile, the University of Illinois licensed the Mosaic technology and name to Spyglass, which wrote its own browser under that license and in January 1995 licensed it to Microsoft, where it became the basis of the first Internet Explorer. So Mosaic’s lineage runs into both sides of the browser war it set off: Netscape was built by its creators to kill it, and Internet Explorer was built under its license to kill Netscape.

Misconception: Internet Explorer was built from NCSA Mosaic’s source code.

Spyglass licensed NCSA’s technology and trademark, but its developer Eric Sink states that “we never used any of the code”: Spyglass Mosaic was written from scratch for Windows, Mac and Unix. Internet Explorer 2.0 was largely Spyglass Mosaic, and IE 6 and earlier still credited NCSA Mosaic in the About box, which is where the belief comes from. See Myths and Misconceptions.

Dead End: The Browser That Lit the Fuse and Was Discarded

NCSA Mosaic itself did not survive the revolution it started. Once Netscape Navigator arrived in late 1994 (built by Mosaic’s own lead developer, faster and more polished) Mosaic’s user base collapsed within a year. NCSA, a research center rather than a software company, had neither the resources nor the mandate to keep pace with a venture-funded competitor sprinting to capture a market. NCSA officially discontinued Mosaic development in 1997.

The Pioneer’s Fate

Mosaic is the archetypal pioneer that gets the arrows. It proved the market existed, defined what a web browser should be, and trained the first generation of web users, and then was destroyed by faster-moving successors that took its lessons (and in one case its license) to market. Being first and being formative are not the same as winning. The team that built Mosaic understood this perfectly: that is why they left to build Netscape rather than defend the incumbent. The most important software is sometimes the software that makes itself obsolete.

Legacy

Mosaic’s fingerprints are on everything you do online. The visual, image-and-text web page; the expectation that a browser is friendly and installs in a click; the very idea that “the internet” is something you look at rather than type commands into, all were normalized by Mosaic in 1993. Its <IMG> tag set the web on its path to becoming the multimedia medium it is today. Its license and name lived on inside early Internet Explorer; its creators built Netscape, whose Navigator lineage (released as open source in 1998) became Mozilla Firefox, still in use today. Even the name “Mozilla,” now a major foundation, is a memorial to the browser Netscape was built to kill.

The web had been invented in 1990. But for most of the world, the web began in 1993, the year they first saw a picture load inside a page.

For the inventor of the web Mosaic displayed, see Tim Berners-Lee and the World Wide Web. For the protocol Mosaic helped bury, see Dead End: Gopher. For what came next, see Marc Andreessen and Netscape and The Browser Wars.

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