Notes: If you don't see the security key option, it's possible that your organization doesn't allow you to use this option for verification. In this case, you'll need to choose another method or contact your organization's help desk for more assistance. Before you can register a security key, you must have at least one additional security verification method registered.

Xbox Support ... Xbox Support

瞭解如何在行動裝置、Windows 裝置或 Xbox 主機上兌換 Microsoft/Xbox 禮品卡或其他代碼。

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 It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired.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

A popular tactic of criminals is the "fake order" scam. The way it works is that you get a message, usually in email or text, that appears to be a routine confirmation for an order. Of course, you never ordered whatever product or service it's confirming. The message looks common enough, and it says that money will be charged to your credit card or withdrawn from your bank account for the ...

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

Sign-in options Usage Guidelines URL: Privacy Policy URL: ...

This security update includes fixes and quality improvements that are part of the following updates: December 9, 2025—KB5071546 (OS Builds 19045.6691 and 19044.6691) December 18, 2025—KB5074976 (OS Builds 19044.6693 and 19045.6693) Out-of-band The following is a summary of the issues that this update addresses when you install this update. If there are new features, it lists them as well ...

Training: Get started with SharePoint in Microsoft 365. At office.com, sign in to SharePoint, then select the SharePoint tile.