Microsoft prioritizes account security and works to prevent people from signing in without your permission. When we notice a sign-in attempt from a new location or device, we help protect the account by sending you an email message and an SMS alert. If your phone number or email changes, it's important to promptly update the security contact info on the Security basics page so we can work with ...

Certificate authority (CA) A certificate authority is an entity similar to a notary public. It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired. Top of Page Digital signature assurances The following terms and definitions show what assurances are provided by digital signatures. Authenticity The signer is ...

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Learn how to identify and open encrypted and protected emails no matter what email client you're using.

The Microsoft Authenticator app helps you sign into your accounts when you're using two-step verification.

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Get a list of speech skills and voice commands you can use with a digital assistant on your Xbox console.

To learn about digital signatures (also known as digital ID), what they can be used for, and how to use them in Word, Excel, and PowerPoint, see All about digital signatures. Create a signature line in Word or Excel (desktop) In the document or worksheet, place your pointer where you want to create a signature line. On the Insert tab, select Add a Signature Line in the Text group. In the ...

Caution: As soon as you create a new recovery code, any previous codes will no longer work.

Learn how you can use the free Microsoft Authenticator app to sign in to all your accounts without using a password.