Mosaic 1.0: 33 years of the browser that invented the visual web

Have you ever stopped to think what the internet was like before you could see a photograph inside a page? Before the animated GIF, before the advertising banner, before any inline image on a web page at all? It was 1993, and the World Wide Web that Tim Berners-Lee had created three years earlier was a network of text. Blue underlined links, monospaced fonts, zero images. About as pretty as a medicine leaflet. Exactly 33 years ago, on 22 April 1993, a 21-year-old university student called Marc Andreessen released Mosaic 1.0 — and put an image inside a browser page for the first time. That was the beginning of everything.

The web before Mosaic: a desert of text

Tim Berners-Lee created the World Wide Web at CERN in 1991. As a protocol it was brilliant — HTTP, HTML, hyperlinks — but the browsers of the era were primitive. WorldWideWeb (later renamed Nexus), written by Berners-Lee himself, ran only on NeXT machines. Lynx, released in 1992, was plain text in a terminal — functional for anyone who knew what they were looking for, invisible to everybody else. To view images, you had to download a separate file and open it in another program. It felt more like querying a database than browsing. The web existed, but it wasn't inviting anyone in.

Two blokes and an after-hours project

Marc Andreessen was 21 and working as a part-time programmer at the NCSA — the National Center for Supercomputing Applications — inside the University of Illinois at Urbana-Champaign. Eric Bina, a more experienced colleague, was the other half of the pair. The two started writing Mosaic in December 1992, largely outside official working hours. The idea was straightforward: a browser with a graphical interface, available for Unix, Windows and Mac, capable of showing images directly on the page — alongside the text, with no helper program required.

Version 0.5 came out in January 1993 for Unix systems. Version 1.0, polished and documented, was released on 22 April 1993. Free. To anyone with a computer and a connection.

The detail that looked small and changed everything

What Mosaic did that the others didn't seems obvious now, but it was revolutionary at the time: it displayed images inline, that is, inside the page itself, side by side with the text. Like a magazine. Like an illustrated book. No separate program, no extra download. You opened the URL and the image was there, in the middle of the content.

Beyond images, Mosaic brought support for forms — essential for any online interaction beyond passive reading — along with bookmarks, browsing history and an interface anyone with a mouse could operate without reading a manual. It ran on Windows 3.1. It ran on the Mac. It ran on Unix. It was the first genuinely cross-platform browser with a graphical interface.

The explosion nobody had predicted

In December 1993, the New York Times ran a story about Mosaic on the front of its business section. The NCSA was already recording more than 5,000 downloads a month — an impressive figure for a niche academic tool distributed in the middle of the dial-up modem era. The web began growing at a speed that left everyone open-mouthed. No longer a tool for researchers in a lab, but a mass communication medium. Companies started building sites. Magazines printed web addresses on their covers. The internet left the university campus and moved into newsrooms, offices and homes.

From Mosaic to Netscape — and the accidental origin of Internet Explorer

In 1994, Andreessen left the NCSA and, with Jim Clark (founder of Silicon Graphics), created the Mosaic Communications Corporation — soon renamed Netscape Communications. Netscape Navigator arrived that same year and quickly took over the market: faster, more stable, and launched at the exact moment the web was exploding.

Meanwhile, the NCSA licensed the commercial rights to Mosaic to a company called Spyglass. Microsoft, realising it had slept through a market growing right in front of its eyes, licensed Spyglass's technology and used it as the basis for Internet Explorer 1.0, released in August 1995. Yes — the original IE was, technically, a direct descendant of Mosaic. The browser wars that defined the 1990s began on that server at the University of Illinois.

33 years on

Mosaic wasn't just a piece of software. It was the "on" switch for the internet as a human experience. Before it, the web was a promise made by technologists. After it, it was product, market, culture, routine. Marc Andreessen was 21 when he started writing the code. A few years later he would found Netscape and become a billionaire. Today he's a partner at the venture capital firm Andreessen Horowitz (a16z). The young man who invented the modern browser now funds the next generation of inventors.

But the real legacy is in the 33 years of browsing that followed that 22 April 1993 — in every image you open in a tab, in every link you click without thinking, in every site you visit without having to download a thing. All of it started with two blokes working after hours in a lab in Illinois.

Do you remember the first time you browsed the internet? Tell me in the comments. And if you want more computing history served with a side of nostalgia, have a look at the post on Winamp, which turned 29 yesterday here on the blog.