Microsoft created the XMLHttpRequest standard; it was first featured in Internet Explorer. Microsoft was also one of the first backers of jQuery.

Mozilla owes much of its market share to the EU, which forced Microsoft to bundle competing browers with Windows, and to the collapse of Netscape in the first dotcom bubble.

Mozilla owes almost none of its market share to the EU. We earned almost all of our marketshare well before the EU decision requiring microsoft to advertise (not bundle) alternative choices and since that change in the EU a couple of years ago, we've seen very little movement in our user numbers. It may prevent IE from getting as many users, but it splits those users among Firefox, Chrome, Opera, Maxthon and others.

Yeah MS fucked up enormously when they created XMLHttpRequest - that is what is so special about it.

So the interesting question is, why didn't Microsoft hop into the Web with both feet in the late 1990s back when it owned personal computing via Windows monopoly? Why did MSIE stall out at IE6 for so long?

Hindsight is always 20-20.

We can only speculate at this point, but if we take a look at the timeline for the browser wars, we get some interesting insight.

From the mid 90's through 2000, we had Netscape as a serious source of competition for MS. MS released IE 1-6 between 1995 and 2001. That's 5 versions inside 6 years. Netscape was bought out by AOL in 1998, thus ending the need for MS to continue improving IE6. Now, there were other browsers at that time, as Netscape opensourced the browser code and gave it to Mozilla, but they all failed to achieve traction. Throughout the 5 year period of IE stagnation, Mozilla had the time to start the war machine up again and start pushing out new code. MS knew that FF was coming, and they knew the feature set that FF supported. The answer to this was IE7 in 2005, however it was pretty much too little too late. FF2.0 was released in 2006, only about a half year after IE7. It had all the same features (plus a few additional) but guess what? It had an intuitive UI and worked well, unlike the MS counterpart that still reeked of R&D stagnation. Not to say that MS didn't do good things for the web, just that, without another company to light the fire under their ass, they failed to innovate. And that's pretty much where we are now: Microsoft is trying to build a browser that actually works (IE9 isn't a total failure), and Google/ Mozilla keep them on their toes. It's a win win for the consumer.