Beyond turning on a firewall, the next basic steps to protecting a system are to activate anti-virus and anti-malware software. Windows now provides these functions built-in, in the form of the Windows Defender tool. (Users have the option of turning off Windows Defender and instead using third-party tools.) Windows Defender provides classic, signature-based analysis on a real-time basis. That is, if a user tries to launch a file recognized as bad, Defender intervenes. Note that while IT administrators might also benefit from a management tool to harvest reporting data from Defender, the tool itself operates effectively without any other software installed.
by Concurrency Blog