There was a time in 1998-99 when Internet Explorer 4 / 5 was actually the best browser by far. Netscape 4 was unstable and had completely botched all the fancy new features: its implementation of CSS (brand new at the time) was so bad that even font sizes didn't work right, its homegrown "layers" API for JavaScript DOM access was awful, and many web developers were wishing they could somehow get away with only supporting IE.<p>25 years after the release of IE4, I'm just glad both of those browser codebases are now dead.<p>IE was really done in by Microsoft's "Longhorn" OS project. After Windows XP, Microsoft was planning a very ambitious update that would completely reset core APIs. File systems would be largely replaced by an OS-level database, and the Win32 GUI API would be replaced by an XML-based UI framework codenamed Avalon.<p>A new Avalon browser would ship with the OS, and thus IE + HTML would become legacy technologies as Microsoft confidently assumed most developers would flock to building their web apps in Avalon instead.<p>To Microsoft strategists, it seemed that they had succeeded in containing the web: Netscape was dead, Mozilla had almost no users, Apple was shipping their IE in Mac OS X, Google wasn't on Microsoft's radar, and the HTML standard process was stalled. So while a lot of content was being delivered as HTML4, there didn't seem to be any reason left for Microsoft to invest in IE — they'd already nailed the browser, owned the market, and would push Avalon as the next step.<p>Fortunately, Longhorn failed. Some parts of the project eventually shipped years late as Windows Vista. Avalon became WPF + XAML and still exists in Windows, but the dream of a XAML browser replacing IE was dead.