Collections of user accounts (Local or Domain) that simplify permission management. Instead of assigning rights to each user individually, rights can be assigned to a group and its members will inherit them.
Users can belong to multiple groups and permissions are cumulative.
PowerShell Commands
Local User Groups
Get-LocalGroup: View local user groups.Add-LocalGroupMember: Add user to local group.
Domain User groups
Are managed with the Remote System Administration Tools (RSAT) PowerShell Module which must be installed.
Get-ADUser: View domain users.New-ADUser: Add domain user.Set-ADUser: Modify domain user.