A 'Session' is a single workout session in the gym and represents a cluster of individual Components (e.g. a Warm-up or Resistance Training component). A session file can include 0 or more Components in any order.
A Component is a part of a Session (see Block Creator page for more details on components), for example a warm-up, or a cool-down. The User is currently restricted to one Resistance Training Component per Session. A Session is not considered complete until all Components in it have been marked complete by the User/Athlete in the VBT mobile app.