Acronym for the Microsoft Management Console.
The MMC is a container program for all sorts of "snap-in" programs that do the brunt of system configuration from Windows 2000 up. MicrosoftCorporation describe it as "an extensible common presentation service for management applications."
The great advantage of a Windows server is that anyone can be taught to administer it. The great disadvantage of a Windows server is that anyone can be taught to administer it.
One page links to MMC: