About digital signatures and certificates in Office, and buying a digital certificate from a certificate authority or create your own.

Find out how to update your Microsoft account if you're moving to a new country or region and about the impact of changing regions.

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 It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired.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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This article describes how you can digitally sign a macro project on Windows by using a certificate. If you don't already have a digital certificate, you'll need to get one.

Learn what to do if you get error XBOS3004 when you try to redeem a code you purchased on Xbox One or Xbox.com.

Learn what to do when you receive a NAT type: Unavailable error message on Xbox.

How to create or edit your Outlook signature for email messages. Include your signature, text, images, electronic business card, and logo.

In Microsoft 365 for Business, you can add a company domain name you own so that your users can have email addresses branded with your company name. For example, if your company name is Fourth Coffee, owning the fourthcoffee.com domain and having your company name in your users' emails – such as alex@fourthcoffee.com – helps you brand your business and build trust with your customers. You ...

What is Teredo? Select games like Forza Horizon 3 and 4 use a networking protocol called Teredo for multiplayer gaming on the Xbox network. Teredo is a networking protocol that’s used to establish communications between clients and servers, and to facilitate connectivity between devices behind routers that use network address translation (NAT).