The purpose of creating athlete groups is to control the athletes that users can access in the system; otherwise, all users in an organization can access all athletes to which the organization has explicit access. In particular, third party Service Provider having a contract established with your organization, can be granted one or more Groups of your organization instead by default all athletes.
An Athlete Group only belongs to one organization. If an organization user has been assigned multiple groups to, then the list of accessible athletes for this user is the union of these groups.
It is possible to link an athlete group to a Team, where after the Team and the Group are automatically synchronized (if the name of team change, then also the group changes its name; if a new athlete joins a team, this athlete will also be added to the group; but when the Team is deleted, the Group remains).
Note that whereabouts teams are automatically created in the administration section as a group and can only be deleted if no user has access to it.