In writing Windows 8.1 Field Guide, I was struck again and again by how Microsoft has integrated its online services more deeply into its flagship platform. In this release, it's still possible to sign-in without a Microsoft account, of course, but Windows 8.1 makes that both difficult and impractical. I suspect it's only a matter of time before doing so is compulsory.

Note: Windows 8.1 Field Guide—previously called "Windows 8.1 Book"—costs just $2, and you can contribute in other ways as well. Check out the Windows 8.1 Book web site for the details about this incredible must-have bargain for all Windows users.

The full-court press starts when you install Windows 8.1 or set up a new Windows 8.1-based PC. Microsoft really wants you to use a Microsoft account, and the sign-in screen you see during the Out of Box Experience in Setup suggests at first glance that this is your own only option.

Squint a bit, however, and you'll see a "Create a new account" link. The resulting screen, too, really pushes Microsoft account.

Here, too, there is a subtle link to skip out on Microsoft account, "Sign in without a Microsoft account." And with those hoops skipped, you can indeed create a local account, just like you did for every previous Windows version.

Of course, Windows 8.1 isn't just the desktop environment. It comes with a new mobile environment called Modern, which includes a ton of new mobile apps and settings. And it also features deep integration with Microsoft services, of which Microsoft account and SkyDrive (now called OneDrive) are just the tip of the iceberg. But since these two services are so central to Windows 8.1, let's focus on them for now.

You've just signed in with a local account. Or perhaps you've logged in to your corporate domain. Either way, you're not using a Microsoft account, and if you're suspicious of such things, perhaps you feel like you've gotten away with something. But as it turns out there are two bits of Windows 8.1 functionality that hinge on having and using a Microsoft account.

The first is Windows 8.1's connected mobile apps. Mail, Calendar, People, Xbox Music, Xbox Video and many other bundled Windows 8.1 apps require a Microsoft account. (And many other apps—like the Bing content apps such as News, Finance, Weather and so on—work much better when you sign in with a Microsoft account.) And if you try to use such an app, you're again provided with a fairly heavy-handed attempt to get you to rethink the error of your ways. Surely, you want to switch that local account to a Microsoft account. Surely. (With a domain account, you're given the option to use that account as a Microsoft account, an option that is fraught with its own issues.)

Here again, subtly, is a link: "Sign into each app separately instead (not recommended)." If you choose that option, you can provide your Microsoft account credentials at the app level, not the OS level, and continue using your local account.

And maybe that's what you want. Or maybe you're a diehard desktop user who thinks you will never need those silly Modern mobile apps anyway. No harm, no foul, right?

Not exactly. The second bit of Windows 8.1 functionality that hinges on Microsoft account integration is SkyDrive (OneDrive). And this one is a bit harder to ignore.

There are two sides to SkyDrive integration in Windows 8.1: Content sync and settings sync. Content sync is the ability to access your SkyDrive-based cloud storage—the documents and other folders you store in the SkyDrive service—and to sync that content you wish to use while offline. It's an absolutely wonderful feature, and it's not available to you unless you sign-in with a Microsoft account. And if you attempt to just run the SkyDrive mobile app, you'll be confronted with a new screen: Here, you can't just sign-in with your Microsoft account. You have to actually switch your Windows sign-in from a local account to a Microsoft account. It's not just heavy-handed. It's absolute.

If you follow the link there, you'll be directed to the Account area in PC Settings and prompted to "connect" your local account to a Microsoft account. But this isn't like signing into an app. This changes your sign-in to a Microsoft account. As the resulting notification shows, you're not connecting anything. You're switching.

The other side of SkyDrive integration is settings sync. This is both truly useful and, go figure, applicable to desktop users too, since many of the settings that sync are ... desktop settings. The real kicker here, of course, is that the type of user who would have multiple PCs and thus would like to sync settings between them is more likely to be a power user and thus would be using the desktop. So you may be able to get by without the Modern mobile apps. And maybe you use Dropbox or whatever for document and file sync. But settings sync? That's actually really useful.

And if you check out the settings sync area in PC Settings (SkyDrive, Sync Settings), you'll get the bad news: "Some Windows features are only available if you are using a Microsoft account."

Microsoft account integration is useful and desirable enough that most users will have no issue switching to this type of account. The benefits are just obvious. But it's likewise obvious that we're being pushed to this future and that it's possible some future Windows version will eliminate local accounts all together (or render them so functionally deficient as to arrive at the same conclusion). The sheer number of changes just between Windows 8 and 8.1 support this. It's just really hard to avoid Microsoft account now.

Related to this is the very real need to secure your Microsoft account with two-step authentication. And there are of course side-topics like why you should or should not turn your work email account into a Microsoft account. For now, I recommend getting familiar with your Microsoft account, and getting it shored up from a security perspective. You're going to be using your Microsoft account a lot more going forward, I bet. Microsoft is going to insist on it.

And it's not just Windows of course. Xbox requires a Microsoft account. Skype will soon require a Microsoft account. Office 365 Home Premium requires on. And so on.