Traditionally, groups are enabled to lock tracks together for editing and mixing purposes. Groups, even disabled ones, are also useful for isolating specific tracks in your session. By right-clicking just to the left of a group name in the Group List, you can see the tracks that are members of that group. Since this works whether the group is enabled or disabled, you can group tracks that you might never enable but would still want to view together. For instance, you can group your drum and bass tracks in a disabled "rhythm group" that can be used to show only those tracks while hiding all others.