What is group user?

A group user is a user assigned to a group with set policies. These policies can range from forcing a user to change their password every 72 days, to having to press CTRL+ALT+DEL before they can log in. A good example of where group users are...used... is at a school. Imagine that you are a student, you are assigned a computer from the school. When you get home you really want to install the newest game you just bought, however, when you insert the disk and click install you are presented with the error message, "You cannot install this program because you are not a member of the Administrator Group." As a precaution against viruses that may exploit the schools "sensitive" files the IT department has set up groups. You are a member of the "student" group, who cannot install, uninstall, or change programs. The IT department is a member of the "Administrator" group who can. Groups are just fancy ways to set the computer so other people can't change important files.