This is bound to have been covered already by a thread?
Select multiple activitites in GArmin Connect Activities screen and Join them to make one ride. Useful for when GPS UNit (Edge 810) crashes or there is a user malfunction. Base camp can do this but cadence and hrm data doesnt carry through.
Also the ability to crop a track, remove end section or start section for when you left it on in the car and it thinks that was part of your ride...