Introduction to Windows 2003 Groups
A group can be defined as a collection of user accounts. Groups help to ease the administrative burden of the system administrator by organizing users together, either to assign them permissions to a set of files, folders, or network resources or for the purposes of distributing emails.
There are two types of groups and three scopes for these groups. Two different groups are Security groups and Distribution groups. Three different scopes define where the groups can be used on the Active Directory network and they are Domain Local groups, Global groups and Universal groups.