Windows Defender Offline, previously named "Microsoft Standalone System Sweeper Beta" is a free and portable antivirus tool that allows users to troubleshoot their system (in case of infections) at startup. directly from an external device (e.g USB, CD).
This antivirus tool is fully autonomous and thus provides a response to several types of problems affecting the behavior of PC at startup.
As this is an independent tool Windows Defender Offline must first be copied to an external device (USB/CD) before being used at startup. To start the scan, the user needs to select the appropriate boot option at startup (removable media, via the F8 key), connect the device and restart the PC.