A new method to classify and describe grasping and manipulation is proposed. It is based on a combination of functions of each of the grasping surfaces composing a grasp. The description is illustrated through example grasps and manipulations by a human hand. The proposed method is useful to design robot hands when some specific desired tasks are given. The designing procedure is also illustrated with a solution to an example design problem. Since our description provides neutral expression of desired tasks in a fashion independent from specific hardware, we can expect to obtain the design of a simplified robot hand to satisfy required task conditions with a structure completely different from that of the human hand.