While Windows Defender can’t be downloaded or used on versions of Windows prior to Windows 8, Microsoft does offer a predecessor to Windows Defender called Microsoft Security Essentials that can be freely downloaded and used on Windows Vista and Windows 7 operating systems.
Windows Defender vs. Microsoft Security Essentials
Both of these Microsoft Security Software tools offer real-time protection against viruses, rootkits, spyware and other malicious software as well as features like online and offline system scanning and cleaning. One key differentiating feature, though, is that only Windows Defender offers enhanced protection against rootkits and bootkits.
Windows Defender primarily runs in the background, only notifying users when a specific action needs to be addressed. Users can also run scans on demand if desired or manually update the tool with the latest security definition files.
What Is Windows Defender Offline?
Microsoft also offers a version of Windows Defender called Windows Defender Offline that can be used via a USB flash drive or CD/DVD to help detect and remove specific types of malware that are designed to prevent users from being able to access Windows Defender and other types of anti-malware software.