Signing in to your Xbox account allows you to enjoy various benefits, including:
Syncing user and app data across your devices.
Making in-game and app purchases.
Accessing premium subscriptions, such as Xbox Live Gold and Xbox Game Pass.
Saving game progress and achievements in the cloud.
Customizing your Xbox profile and avatar.
Sharing content with friends and participating in online multiplayer games.
For more www.microsoft.com/link
