Groups in Duplie contain users, access, event roles and admins. The admins can manage the groups, send emails and create events for the group. Groups are an easy way to communicate and send out important information. Users can also belong to multiple groups. Each group can have multiple access rights, event roles AND administrators.
You don't have to create groups for event and role management, but it makes it a lot easier to manage as your organization grows. By default, Duplie will create an initial Admin group that will have the organization creator in it -along with administrator access.
The best feature with groups is users can post messages and upload images to the group which is viewable by all the users within the group. This is a great way to communicate and keep users/volunteers involved.