Microsoft Defender is the simple way to protect your digital life and all of your devices.

Important: This article is about the Microsoft Defender app that is currently in public preview for people to download to protect their personal and family devices including Macs and smartphones. If you're looking for information about the Windows Security app that is built into Microsoft Windows see Stay protected with Windows Security.

Once you've installed Defender on your device, open the app then sign in with your personal Microsoft account to get it set up.


  • Microsoft Defender only supports signing in with a personal Microsoft account (such as,, or

  • Currently, the Microsoft Defender public preview is only available in the United States and only in English.

Once you've signed in, Microsoft Defender will walk you through a brief onboarding process where you'll turn on anti-malware and web protection services for your device.

Microsoft Defender is a security app that helps people and families stay safer online with malware protection, web protection, real-time security notifications, and security tips. Microsoft Defender is included in a Microsoft 365 Family or Personal subscription and works on your phone (Android or iOS), PC, and Mac.

Windows Security, formerly known as Windows Defender Security Center, is an app built into Windows 10 or 11 that helps keep your PC more secure. It includes Microsoft Defender Antivirus, an antivirus tool that helps protect you against viruses, ransomware, and other malware. 

For more information, see Stay protected with Windows Security.

Windows Defender Firewall is firewall software built into Windows that controls which network traffic is allowed, or blocked, from passing to or from a computer across the network or internet. Windows Defender Firewall is on by default. 


Malware is malicious software which can steal or damage your personal data such as files, photos, or messages. It may also track or spy on you, steal your money, or use your device to cause other mischief like attacking other people.

Microsoft Defender can check files or apps you download and install, as well as run scans of files already on your system to spot any malware that may threaten your device.

To learn more about anti-malware see Getting started with anti-malware in Microsoft Defender. 

Tip:  Stay up-to-date and install the latest updates on all your devices and apps (especially browsers) to help prevent malware.

Web protection 

Many of the digital attacks we see are through harmful websites that try to trick you into revealing personal information—such as usernames and passwords, credit cards, or other account information—or installing malware on your system. Microsoft Defender will check links that you (or an app on your device) open to try and spot any that may be dangerous.

If we find a harmful link, we'll block it and let you know. 

To learn more about web protection in Microsoft Defender, see Getting started with web protection.

Tip:  What is phishing? It’s a trick to steal your info or get you to install malware by pretending to be a message from someone you trust. For more information see Protect yourself from phishing.

Adding other devices

You can add up to 4 additional devices (for a total of 5 per person) to your Microsoft Defender account by installing the app on your other devices and signing in using the same personal Microsoft account. These devices will appear on your Microsoft Defender dashboard so you can see the security status of all your devices in one place. 

For more information, see Adding devices to your Microsoft Defender account. 

Helping to protect the whole family

If you're a Microsoft 365 Family subscriber, the people who have the Family Organizer role can help to protect the devices of everybody in the family. When other family members install Microsoft Defender and choose to share their device status, the family organizers will see that status on their Microsoft Defenderdashboard under Other devices.

For more information, See your family's devices in Microsoft Defender.

We'd love to hear from you!

Your feedback is key to making our products better, so if there's anything you like about Microsoft Defender, and especially if there's anything you don't like, please let us know! You can send us feedback in the app by going to the Help and feedback menu.

On Windows or Mac, select the  Help button  button near the top right of the window. On Android or iOS, tap your account avatar at the top left to find Help and feedback.

Visit the Microsoft Defender community on Microsoft Answers! 

Want to ask, or answer, questions about Microsoft Defender? Chat with others who are previewing Defender? Visit the Microsoft Answers community for Microsoft Defender here!

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