Internet Explorer 6 shipped in 2001 bundled with Windows XP. With Netscape already in collapse from the first browser war, IE6 quickly became the overwhelmingly dominant browser. Then Microsoft, having won, largely stopped developing it. For years there was little competitive pressure and little new work, and the web’s most-used browser stood still.
The problem was that IE6 implemented HTML and CSS in idiosyncratic, often non-standard ways. As newer browsers adopted the emerging web standards, developers were forced to write and maintain special workarounds just to make sites function in IE6. It became, in industry shorthand, “the browser that wouldn’t die”: a piece of software that lingered on millions of corporate and home machines long after better alternatives existed, dragging down what the web could safely use.
Eventually the frustration produced organized campaigns to retire it, including efforts by major websites to drop support and nudge users to upgrade. The renewed competition of the second browser war, with Firefox and later Chrome, finally broke IE6’s grip.
Internet Explorer itself is a component of Windows and followed the lifecycle of the operating system it shipped on, as Microsoft’s lifecycle documentation describes. That same documentation records the broader end of the line: Internet Explorer 11 was the last major version, and the IE11 desktop application went out of support on June 15, 2022, with users directed to Microsoft Edge and its Internet Explorer mode. IE6 had long since become the cautionary tale of what happens when a dominant browser stops moving.