Malware is malicious soft ware which can steal or damage your personal data such as files, photos, or messages. Windows Defender Firewall is on by default. Windows Defender Firewall is firewall software built into Windows that controls which network traffic is allowed, or blocked, from passing to or from your computer across the network. It includes Microsoft Defender Antivirus, an antivirus tool that helps protect you against viruses, ransomware, and other malware.įor more information, see Stay protected with Windows Security. 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. Microsoft Defender is included in a Microsoft 365 Family or Personal subscription and works on your phone (Android or iOS), PC, and Mac. 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.