When working with manipulator robots, one of the main goals to achieve is picking up an object from one position, and placing it in another one, which is commonly known as pick and place. We call grasping the process of picking an object up by the robot an end-effector (which can be a hand, a gripper, and so on). Although this may sound like a very simple task, it is not. In fact, it's a very complex process, because lots of variables need to be taken into account when picking up the object.
We, humans, perform grasping by hand using our intelligence, but in a robot, we have to create rules for it. One of the constraints in grasping is force; the gripper/end-effector should adjust the grasping force for picking up the object, but not deform the object while grasping it.