Windows Defender Offline is a new feature of Insider Builds of Windows 10 that enables you to scan the computer system during boot time and without Internet connection requirement.
Windows Defender is the built-in antivirus solution of the Windows 10 operating system. While its capabilities have improved in recent time, it is still inferior when it comes to the detection of malware when compared to many third-party solutions.
The latest
AV Test results published in October 2015 for instance give Windows Defender 14 out of 18 points, but only 3.5 of 6 points in the protection test category which is the lowest score awarded in the test series.
Windows Defender Offline
While that is certainly discouraging, it is positive that Windows Defender's protection capabilities are improving. One of the latest improvements that is currently available only to Windows Insiders on Windows 10 is a new option to run a system scan on boot instead of while the system is running.