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 It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired.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 ...

在Outlook中，你可以為電子郵件建立一個或多個個人化簽名。 你的簽名可以包含文字、連結、圖片和圖片 (，例如你的手寫簽名或標誌) 。

In certain countries and regions, PayPal can be used as a payment option to buy subscriptions like Game Pass and content such as games, apps, music, HD movies, and TV shows on your Xbox Series X|S console, Xbox One console, Xbox 360 console, and Xbox.com.

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

Learn how to sign in and create app passwords for Microsoft apps and devices that don't support two-step verification.

A digital signature attached to an email message offers another layer of security by providing assurance to the recipient that you—not an imposter—signed the contents of the email message. Your digital signature, which includes your certificate and public key, originates from your digital ID. And that digital ID serves as your unique digital mark and signals the recipient that the content ...

Get help if you're having problems sending someone a digital Xbox game or subscription as a gift.

Note: For information about signing in using the Microsoft Authenticator app see the article, Sign in to your accounts using the Microsoft Authenticator app.

Learn more about how Xbox cloud gaming works on iOS mobile devices.

With two-step verification, you'll get a security code to your email, phone, or authenticator app every time you sign in on a device that isn't trusted. Need more help?