With Project Spartan, Microsoft is building a new, modern browser for all Windows 10 devices: PCs, tablets and phones. Although the new rendering engine (Edge) has been forked from the one in Internet Explorer 11 (Trident), it has rapidly diverged from it, and now works well if websites treat it as Google Chrome. However, what may be more important is what Microsoft is leaving out, which is IE's historical baggage.
The Spartan codename presumably refers to the Xbox One game, Halo: Spartan Assault, which befits a new assault on the browser market. To those more familiar with ancient Greece than Draetheus V, it has stronger connotations of the city-state famous for the toughness and military prowess of its people. Even today, "Spartan" connotes "sternly disciplined and rigorously simple, frugal, or austere".
Of course, Google must be aware that today's Chrome is becoming increasing bloated, swallowing more memory and resources than its main rival, Firefox (1). We assume this is one reason why Google forked WebKit to create its own Blink, which is also dumping historical baggage. (Not having to work with Apple is probably another.) But Internet Explorer goes back 20 years, and Microsoft has a lot more baggage to dump.
As Microsoft's Jacob Rossi told Smashing Magazine last month: "swathes of IE legacy were deleted from the new engine. Gone were document modes. Removed was the subsystem responsible for emulating IE8 layout quirks. VBScript eliminated. Remnants like attachEvent, X-UA-Compatible, currentStyle were all purged from the new engine. The codebase looks little like Trident anymore (far more diverged already than even Blink is from WebKit)."
Given that IE11 is, in most respects, already competitive with Chrome on Windows 8.1, the improvements from Project Spartan could put it significantly ahead.
The Project Spartan team is also fixing thousands of interoperability bugs and adding support for dozens more web standards: see modern.IE for progress reports.
The most important question for businesses is "What happens to websites and intranets built for early versions of IE?"
Jacob Rossi's answer is that "Windows 10 will use EdgeHTML for the web (so no more worrying about doc modes) and only load Trident for legacy enterprise sites. This dual-engine approach enables businesses to update to a modern engine for the web while running their mission critical applications designed for IE of old, all within the same browser."
However, in "Windows 10 as a service," the new browser will be rapidly and continuously updated, just as Chrome, Firefox and most web apps and services are today.
From the comments, it's obvious that Microsoft will have to overcome a major challenge to its credibility, but many of the objections are based on ignorance. There's a whole generation of web developers who don't appreciate that IE6 wasn't just dramatically better than Netscape when it appeared in Windows XP in 2001, it was also more standards-compliant. Some even seem to blame Microsoft for the fact that IE6 doesn't support standards that weren't written until years after it came out, and that many organizations used XP long after Microsoft tried to wean them off it.
There are also comments from people who don't seem to be aware of anything that's happened to Internet Explorer in the six years since IE8, if not longer. However, this could be to Microsoft's advantage, because the Spartan browser will look a lot better against IE6-8 than against IE11. If they can be persuaded to give it a fair trial.
There are, of course, many things we still don't know about the Spartan browser. One is how much RAM and resources it will devour, because this must be the key competitive advantage against Chrome. (It's one that the "back to Firefox" bandwagon is already exploiting.) Another is the final name.
It's possible that the project name will become the brand name - as happened with the Xbox and the Halo-related Cortana - but this seems unlikely with Project Spartan. Maybe something snappy with One in it? I just hope it's not called Internet Explorer. As IE11 is demonstrating, that has enough negative connotations to drown out real advances in quality and performance.
(1) Bloatware is what happens when you build your own operating environment - user IDs, accounts, apps, notifications, security sandbox etc - inside somebody else's operating environment. Just try comparing a blank Google Doc in Chrome with a blank document in a recent copy of Microsoft Word.