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 It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired.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

Find out how to submit a request for a refund for a purchase of digital Xbox content.

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) 。

This article explains how you can get or create a digital signature for use in Office documents. To learn more about how to use them in Office documents, see Add or remove a digital signature in Office files. What is a digital signature? A digital signature or ID is more commonly known as a digital certificate. To digitally sign an Office document, you must have a current (not expired) digital ...

Here are the most likely causes for an unrecognized charge: A Microsoft subscription has recurring billing enabled. Someone you know, such as a family member, bought something with your card. You can now investigate this on the Manage your payments page. A previously declined charge was charged again. A pre-order or split order was shipped. Someone made an in-app purchase from an app, game, or ...

What is Secure Boot? Secure Boot is a security feature in Unified Extensible Firmware Interface (UEFI) based firmware that helps ensure that only trusted software runs during a device's boot (start) sequence. It works by verifying the digital signature of pre-boot software against a set of trusted digital certificates (also known as certificate authority or CA) stored in the device's firmware ...

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

Important: You don't need to remove old security information unless there is an account security risk (e.g. someone else has access to your old mailbox). If you do need to replace your security information, make sure you add new information first. If you request removal of all security information in your account, the account is put into a restricted state for 30-days. Your information doesn't ...

Learn how to cancel your Microsoft subscriptions such as Microsoft 365, Copilot Pro and Xbox. Troubleshoot issues if you can't cancel your subscription.

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 ...