I’m writing this paragraph in Word for Windows on Windows 10. The process is as smooth as you’d expect on PC hardware built for Windows, with no hesitation or freezing, and all the features are enabled. But I’m not using a Windows PC; I’m using a three-year-old MacBook Air. And I haven’t had to give over the Air entirely to Windows. Instead, I’m running Windows 10 and its apps concurrently with the brand-new macOS Sierra. For instance, the Windows version of Word is running in its own window, right alongside open Mac apps, including Apple Mail and Safari.

I’m doing this all with the new version of a 10-year-old program, Parallels Desktop, from a Seattle-area company of the same name, which came out last month for $80. It’s faster and smoother than ever, and has some new tricks, including a new Mac utility suite that’s also sold separately.

With ParalleIs Desktop, I can hop back and forth between Sierra and Windows 10 — and even between individual apps — with ease. I just copied and pasted the paragraph above into Apple’s proprietary Notes app, exactly as I could from a native Mac app. And I wrote this sentence in Notes and copied and pasted it back into the Windows version of Word. Then I copied and pasted the whole thing again from Word for Windows into Google Docs running in Safari natively on the Mac.

Through all this, the aging Air performed smoothly and quickly, even though I’m now running three Windows apps and 11 Mac apps, including two browsers — Microsoft Edge and Apple Safari — with about 15 tabs open, total. That includes two instances of the constantly updating TweetDeck app for Twitter power users.

The only sign of strain is the constant, low whir of the fans. But, to be honest, my faithful Air cranks up the fans pretty often these days even when running just macOS, and did so even before Sierra. (God, I hope Apple gives the Air a power bump, and soon.)

When Parallels first came out, in 2006, I called it “a pleasure to use” and “the best of both worlds.” After using this new version, Parallels 12, I can say with confidence that, in my tests, it still is. If you love and use the Mac, but need to use a few Windows apps, Parallels does the trick.

The world has changed

However, the world has changed a lot since then, and the need for Parallels has diminished for average Mac users. When it was launched, shortly after Apple switched the Mac to the same Intel processors that Windows used, it was a big deal, because there were still lots of apps only available for Windows, or which — like Microsoft Office — were vastly better on Windows.

Parallels also offered a smoother solution than Apple’s own method for solving this problem: a feature called Boot Camp that’s still built into the Mac. Boot Camp also allowed running Windows on a Mac, but it required you to carve out a separate Windows partition on your hard disk, and you could only run one OS at a time. You had to reboot each time you wanted to switch.

Now, however, the web and web apps have drastically reduced Mac users’ need to run local Windows apps. Macs have become more common (though still a minority of PCs) and app makers have produced many more good Mac-native apps than existed in 2006. Even Microsoft has brought the native Mac version of Office far closer to parity with the Windows version.

Perhaps even more important has been the rise of smartphones and tablets, where Apple maintains a strong position. Many PC use cases have moved to mobile apps, and Apple’s iOS mobile operating system gets excellent versions of these apps, and often gets them first. The Mac-Windows rivalry has been replaced by the iOS-Android rivalry, and iPhone and iPad users aren’t at an app disadvantage.

But some still will find it useful

So why would anyone still need or want Parallels?

Well, some programs and sites, especially in banking and finance, are still Windows-only, or still require Internet Explorer, which lacks a Mac version. Some people who work for big companies still need to use in-house apps that run on Windows only. Some power users of Office still prefer the Windows version. Developers also find it useful. And Parallels doesn’t just run Windows 10: it can run multiple versions of Windows, Linux, and even older Mac operating systems in virtual machines.

Plus, heavy-duty PC games are still written almost entirely for Windows.

Parallels can solve the first set of issues, but, while it has gotten better at Windows games, it can’t handle enough of them well enough for me to recommend it to gamers. (The company does say that Parallels 12 can, with the proper settings, let you play Blizzard’s Overwatch, as an example. And it says it can handle the Xbox app on Windows 10, because the Xbox is doing the work. But I didn’t test games.)

Interoperability between the two systems is impressive, and goes well beyond copy and paste. For instance, I was able, on the first try, to get Apple’s Siri (now on the Mac) to launch the Windows Calendar app and to get Spotlight to launch Groove Music on Windows. And I was able to get Cortana, the Windows assisant, to launch Keynote from the macOS. Icons for Windows 10 and for individual Windows programs you’re using show up in the Mac’s Dock just like Mac apps, and can be kept there permanently if you like.

On the Windows side, Mac folder icons live on the desktop next to local Windows ones. You can open and work on Mac files with your Windows apps. And a C: drive appears in the Mac Finder’s list of sources, so you can call up Windows files. The Mac’s Command key works as the Windows key when you’re using Windows.

Parallels has always stored its virtual machine in a big file in the Documents folder on the Mac, which also includes files you saved to the virtual PC. But it takes up less room than you’d think, and, in Sierra, this big file can automatically be moved to the cloud. In my tests, Parallels 12 cost me only about nine gigabytes, even though I have two Parallels virtual machines: a new Windows 10 one and an older one running Windows 8. Fetching things from the cloud worked quickly.

A new utility

The company is also touting a new companion utility, called Parallels Toolbox, which lives in the Mac’s toolbar and lets you do a variety of things with one or two clicks. These include locking the screen, muting the mic, archiving files, downloading streaming media from the web, and recording actions on the screen. It works whether you’re running Mac or Windows at the moment. In my tests, it worked well, and the company says it will add more features over time. But it’s expensive for a utility bundle, at $10 a year. (A basic version is bundled with the standard edition of Parallels Desktop; the edition which will get more features is included with pricier Pro and Business versions of Parallels, which cost $100 a year.)

Pricing

As noted above, the basic edition of Parallels 12 costs $80, at parallels.com. But unless you got it as a free upgrade, you’ll also have to buy Windows 10. I bought a copy for $120, using a very nice Parallels wizard that takes you to Microsoft’s web store to buy it, then installs it for you. It will also install a legal disk image of Windows if you get one elsewhere.

Bottom line

I have a soft spot for breakthrough products like Parallels, even years after they appear. I remain impressed by its quality and performance. And I can recommend it for developers, or average Mac users who just need to use a few Windows apps.

Correction: an earlier version of this column mistakenly omitted the fact that a basic version of Parallels Toolbox is bundled with the standard edition of Parallels Desktop.