The very first proper graphical browser ever released was NSCA Mosaic, a browser for Unix on the X-window system it was released less than a year after the first Linux kernel was released. Within a few years the browser was comercialized and became the netscape browser. Gaining a port for Microsoft Windows 95 it became the first browser of choice on that platform and while the Unix version persisted it was rather neglected in those years.
Netscape on Windows took a major hit when Windows 98 shipped with internet explorer built-in, and around this time something else very importantly changed in the Free Software world. It was in this time that Eric Raymond wrote "the Cathedral and the Bazaar" the first study of free software as a technical development methodology rather than just an ethical stand-point. While there is nothing wrong with such a study it would ultimately lead to a rift between those whose primary motivation was ethical (like Stallman) and those who cared only about practical advantages.
Back in 1998 however, this was hardly an issue yet and it would begin a major change. Raymond's book caught the eye of Netscape's executives and it was from one of them that the phrase "open-source" came. Netscape saw a shot at survival there and began a process to release their source code.
The initial model had netscape kept as a commercial browser with extra features built on top of the structures produced from the open code-base they called Mozilla. Mozilla in those days was a much needed tool – and every developer's nightmare. The codebase was notoriously ugly, absolutely gigantic by Linux standards and frequently very badly written and designed. The mozilla foundation and their largely volunteer developer base knew it would take years to refactor and improve that code, and thus chose to release incremental process through what was known as milestone releases.
Most hardcore geeks would regularly download and build the latest mozilla milestone, a task which on the computers of the time would easily ran overnight and into the next morning – and was fraught with risk, many times it would fail after many hours due to a new bug that had not been picked up upstream.
Distro's would get the best build they can and include those and then released binary builds incrementally as updates on a much slower pace (mostly because it was jut not practical to do more) and this is what we browsed the web with. By then IE6 was the dominant browser on the web, and mozilla's market share was tiny – the result was that most web designers simply didn't care to follow standards (especially since neither browser did that well) and just developed their pages to work in IE. Even major banking and government institutions often didn't work. It could get worse, at one point South Africa's independent electoral commission's website did a browser-check and if you were found not to be running IE6 would redirect you to a page instructing you to get "a real browser". Alistair Otter of tectonic news had a field day with that one !
That state would last for several years as the mozilla code-base was improved and slowly trimmed down. Mozilla as a browser would not ultimately survive but from it's core code base and gecko rendering engine would ultimately come Mozilla Firefox (a side story – this new browser project designed to be a fast low-resource browser using the gecko engine was originally called FireBird, but the then long established developers of the free FireBird SQL server complained about this bad form among fellow FOSS developers and the name was changed – this was the start of several such events, later issues about trademarks from Firefox led to many distributions making minor forks that only changed the name and branding – debian being the first, and ultimately the FSF themselves created a major fork stripped of non-free bits and it's own addon site that only allowed free software addons – this version is called IceFox) , from Netscape Mail would come Thunderbird, and even Eudora persists.
In fact the list of Mozilla based applications has gotten quite huge and the mozilla corporation is one of the flagships of the free software world today. Looking at the ease with which we can load up multiple standards compliant free browsers today (Google's Chromium, Firefox etc.) and be quite confident of almost never finding a site they can't handle is a stark contrast to those early days when we frequently felt the annoyance of a website refusing to play nice, when most of us changed our user-agent to try and convince the sites we were running IE6 so we could get around browser-filters and when getting an update for security and features meant downloading a source package larger than the kernel with a hugely complex (and atypical) build process that was truly fragile and took a very long time even if it work.
But we did it anyway – and it paid off.