On Windows 11 (and 10), Microsoft Defender Antivirus is a security feature that protects your computer and data from virtually any type of malware and hackers. Although this is one of the best antivirus software, it's not perfect, and sometimes, specially crafted malicious code can find its way into the system, rapidly take control, and cause irreversible damage.
This is not specific to Microsoft Defender. It can occur with any third-party antivirus you install on your computer. However, if your device gets infected with nasty, hard-to-move malware when Windows is loaded, you can use the Microsoft Defender Offline scan option. The offline option is an automated feature capable of running when the system isn't active, which allows the anti-malware engine to detect and remove most viruses more easily.
