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Windows 10 includes an Xbox app and other Xbox-related features. Many of these features are useful even if you've never owned an Xbox in your life, and one of these features is even useful for Windows 10 users who never play games.
This isn't the first time Microsoft has attempted Xbox integration with Windows. Microsoft tried that with Games for Windows LIVE, which launched nearly a decade ago back in 2007. But Windows 10's Xbox integration seems to be a better effort than Games for Windows LIVE was.
A Built-in Screen Recorder
Let's lead with the most useful feature. Windows has a built-in screen record that can be useful even to people who aren't PC gamers, but it's sadly buried in the Xbox app where many people won't find it.
The Game DVR feature is designed for you to record your gameplay and share it. However, you can use it to record any application, making this a built-in screen-recording tool for more than just games. You can launch the "game bar," which contains a recording option, by pressing Windows Key + G by default. This keyboard shortcut can be customized in the settings inside the Xbox app. Click the "Record" button on the game bar to start and stop recording.
The Xbox app can help you upload and share the clips, but they're just video files you can access on your hard drive.
Xbox One-to-PC Streaming
If you own an Xbox One, you can use the Xbox app to stream games from it to your PC over your local network. Even if your Xbox One is in your living room hooked up to your TV, you can connect an Xbox One controller to your PC and play Xbox One games. The Xbox One does the work and streams it over the network, allowing you to play those games at your computer. That means your spouse or roommate can use the TV while you keep up your Destiny streak. To do this, open the Xbox app, click the "Connect" button at the bottom-left corner, and connect to your Xbox One. You'll be able to stream games to your PC from here.
It's basically the opposite of Steam's game streaming or NVIDIA's game streaming--instead of streaming games from the PC to your living room, it allows you to stream games from an Xbox One to a PC. Microsoft has hinted that PC-to-Xbox streaming may arrive in the future, allowing you to stream PC games and play them on a TV an Xbox One is hooked up to.
Sony has promised to offer PlayStation 4-to-PC streaming soon, too. There's already an unofficial solution, and a way to stream PS4 games to any Android device.
A Window to Xbox Live
The Xbox app included with Windows 10 is essentially a window to Xbox Live on your PC. It features a friends list, allowing you to chat on Xbox Live or join a party from your PC. It also includes an activity feed, a store you can use to purchase Xbox One games from your PC, your gamerscore, and achievements. Connect the Xbox app to an Xbox One console and you can view TV listings, too.
Most of the features here will only really be useful to people who already have Xbox One or Xbox 360 consoles, although Microsoft is aiming to hook more Windows games into its Xbox services. It's doing this through the Windows Store, releasing more and more PC games that are integrated with Xbox. Only games from the Store can have that Xbox integration, it seems. Rise of the Tomb Raider has Xbox integration if you buy it from the Windows Store, but not if you buy it from Steam.
The Xbox app will sign you into Xbox Live with the Microsoft account you sign into Windows 10 with by default, but you can choose to sign in with a different Microsoft account if you have those accounts separate. It doesn't require a paid Xbox Live Gold subscription for anything.
Xbox Achievements, Cross-Buy, and Cross-Platform Multiplayer
Games you purchase--or download for free--from the Windows Store can integrate with Xbox. In fact, the Xbox app itself contains an "Xbox Store" section that allows you to browse and purchase games from the Windows 10 Store. Essentially, it provides another window to the Windows Store.
Currently, many games offer Xbox achievements that can add to your gamerscore--something you probably don't care about unless you're an Xbox gamer. The Solitaire app included with Windows 10 is a good example, as it's integrated with Xbox and provides achievements and gamerscore points. Microsoft's Minesweeper app, which is available from the Windows Store, also provides Xbox achievements.
However, games can also offer more useful Xbox integration. Some games are beginning to support cross-buy--if you purchase Quantum Break, you'll get it for both Windows 10 and Xbox One. Future games may support cross-platform multiplayer between Windows 10 and Xbox One, so you can play on your PC with your Xbox-using friends.
Not all games are guaranteed to support these features, but they can. For example, Rise of the Tomb Raider, the first big-budget PC game to appear in the Windows Store, doesn't offer cross-buy between Windows 10 and Xbox One. It also doesn't offer cross-platform multiplayer, although it does link to Xbox to offer achievements and gamerscore points. Games in the Windows store definitely have their problems, but if they included some of these features, it might be a bit more enticing.
Music, Movies, and TV
The Groove Music and Movies & TV applications included with Windows 10 were previously named Xbox Music and Xbox Video. You can subscribe to Microsoft's music service and play games on your Xbox, or rent and purchase movies and TV shows from the Windows Store. If you do, you can watch them on either your Windows 10 PC or Xbox--they're tied to your Microsoft account.
To buy digital videos or music, open the Windows Store on your PC. You can then open the Movies & TV and Music apps on your Xbox and you'll find the same content you purchased or rented there, too.
Microsoft is working on bringing Windows 10 apps to Xbox One, which would allow those same apps to run on Xbox. This may mean you could purchase an app from the Store and install it both on your Windows 10 PCs and Xbox One one day soon.