Windows 2003 TechNotes

The main purpose of a group is to simplify administration by allowing permissions to be assigned to a collection of users instead of individual users. A group can contain user accounts, computer accounts, or contacts, as its members. In addition to the previous, a group can also contain other groups, which is referred to as group nesting. Which items a group can contain and where they can be used for, depends on the group type, the group scope and the domain functional level.