An arm is a limb. Most humans have two arms each, coming out of their body at the shoulder, just below the neck. On the end of each arm is a hand. Humans use arms and hands to do things to other objects, this is called manipulation. The main purpose of the hand is to grasp objects. Some other primates have arms which they use to move around by holding onto trees or supporting themselves as they walk along the ground. Fingers and hand, wrist, forearm, elbow, upper arm and shoulder are parts of the arm. 