Add or remove a digital signature in Office files. Get a digital ID. Find digital ID or digital signature services. About digital signatures and certificates in Office, and buying a digital certificate from a certificate authority or create your own.

To digitally sign an Office document, you must have a current (not expired) digital certificate. Digital certificates are typically issued by a certificate authority (CA), which is a trusted third-party entity that issues digital certificates for use by other parties.

Learn how to redeem a gift card, code, or Office product key and spend your balance at Microsoft Store online, on Windows, or Xbox.

There are different ways to remove apps and programs, so if you can't find the one you're looking for, you can try another location. Note that some apps and programs are built into Windows and can't be uninstalled. You can try to repair a program first, if it's just not running correctly.

Cast to a display from a Windows PC. You can wirelessly connect your PC to a TV, projector, or other kind of external display that supports Miracast. Turn on your TV, projector, or other display. If you're using a Miracast dongle or adapter, make sure it's plugged in to the display.

Activate Microsoft 365 or a non-subscription version of Office. When you start an Microsoft 365 app that's not activated, you'll be prompted to sign in to Microsoft 365. Be sure to sign in using the Microsoft account, or work or school account, that you used to buy or subscribe to Microsoft 365.

Check for Windows updates. Learn how to update drivers in Windows using Device Manager to update or reinstall a driver.

For Microsoft 365 operated by 21 Vianet go to login.partner.microsoftonline.cn. For Microsoft 365 Germany go to portal.office.de. This completes the download of Microsoft 365 to your device. To complete the installation, follow the prompts in the "Install Microsoft 365" section below.

It looks like this: PRODUCT KEY: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. Locate your product key for Windows 10 or Windows 11. Depending on how you got your copy of Windows 10 or Windows 11, you'll need either a 25-character product key or a digital license to activate it.

This article applies to Office Home & Business, Office Professional, and individually purchased Office apps. To switch an Office install to or from Microsoft 365, see Switch your Office license. How you change the product key depends on your version of Office. Select your Office version from the tabs below.