Before you begin
Version: v6 (what does this mean?)
User groups are sets of permissions that can be assigned to users. These permissions are site-specific, and only apply to each site that the group is active in. This is similar to roles, with the difference that roles apply to all sites while groups are site-specific.
If a user needs different levels of access in different sites, configure their account so that they're assigned to different user groups at different sites. For example, if a user manages Site A, but occasionally does work at Site B, you could assign them a user group with more access for Site A, and one with less access for Site B.
If your organization operates with only one site, then roles and groups fulfill similar functions.
To learn more about user groups, see the following articles: