A joint is an object that has at least one intrinsic Degree of Freedom (DoF). Joints are used to build mechanisms and to move objects as can be seen in following figures:
[Robotic manipulator (left) and visible joints/motor (right)]
Joints are added to the scene with [menu bar --> Add --> Joint]. Refer to the joint section in the model creation tutorial. Some joint data can be recorded by graph objects. Refer to graphs and graph data streams for more information about how to record joint data.