Google CEO Sundar Pichai YouTube Today, two very important things happened for the future of the PC as we know it.

First: For the first time ever, low-cost Google Chromebook laptops outsold Apple's Macs during the most recent quarter, analyst firm IDC tells The Verge.

Manufacturers including Dell, Lenovo, and HP sold over 2 million Google-powered Chromebooks combined, versus around 1.76 million Macs, IDC estimates.

Second: those same Google Chromebooks are getting full access to Android's Google Play store, opening the door for those laptops to run a significant portion of the 1.5 million Android apps out in the wild.

For Apple, it's not necessarily great news, but it's not the end of the world, either. Quarter after quarter, Macs have shown sales growth, bucking the overall shrinkage of the PC industry. And Apple has always been a company that's content to completely and profitably own a small piece of a much larger pie.

But for Microsoft, it means that the pressure is on — Google's slow-but-steady attack is bearing some real results, and it's not great news for Windows 10.

Why people like Chrome

The key concept of the Chromebook is simplicity and portability. These devices run Google's mega-lightweight Chrome OS, which is little more than a web browser. That works fine, given that the vast majority of stuff that most people do on computers is based around the browser, anyhow.

That limitation becomes a strength, too: Because so little data is stored locally, it means that nothing is lost if you break or lose a Chromebook. It's all in the cloud, no matter what. And because the technical requirements for running a browser are so low, you still get reasonable performance, even from a sub-$200 laptop.

The Asus Chromebook C201 is a sub-$200 laptop that runs Google's Chrome OS. Google

That combination of low cost and resiliency is an offer that lots of schools, especially, can't refuse. Chromebooks continue to see their strongest growth in the educational space.

Add Android apps to that mix, and it gets even better. Android is the most popular operating system in the world. Any software today is likely going to be available on Android, the web, or both. It means that for Chromebooks, and indeed any Chrome OS device, there's basically nothing you won't be able to do.

Google is basically taking its wildly successful smartphone operating system and smashing it together with Chrome OS to make it a more useful desktop operating system.

Microsoft is taking the opposite tack with Windows.

Where Windows 10 is going

With its Universal Windows Platform iniative, Microsoft is trying to convince developers — mainly the new breed of smartphone app developers — to bring their services to Windows 10 and its Windows Store.

It's basically trying to take its existing lead in desktop operating systems, and extend it down to the things people usually do on their phones nowadays.

They've had some success at attracting big names like Uber, Facebook, and Hulu, but Windows 10 just doesn't have the same thriving ecosystem of, say, Google's Android. Thanks to Microsoft's lack of presence in the smartphone world, many developers would rather focus their efforts on iOS and Android.

A slide from Microsoft's GDC 2016 talk. Matt Weinberger/Business Insider For now, that's fine. Windows 10 still runs all of the old-school Windows software that consumers and business are used to, and you can still use your web apps. Increasingly, though, the next generation of great stuff is being written for the smartphone, or for the web, because that's where the customers are.

It's a future that Chromebooks will be uniquely well-positioned to take advantage of, with that all-important community of Android app developers, plus the mega-popular Chrome web browser.

And while Google doesn't make its own Chromebook laptops, with the exception of the super-high-end Chromebook Pixel line, the Chromebooks represent significant new territory for Google's Android business and overall reach.

Windows still has a clear lead now, but the PC market is shrinking, with little chance of a turnaround. If Chromebooks are growing amid those conditions, it's just another challenge for Microsoft to overcome.