Massage is the manipulation of superficial layers of muscle and connective tissue to enhance the function and promote relaxation and well-being. Massage involves acting on and manipulating the body with pressure – structured, unstructured, stationary, or moving – tension, motion, or vibration, done manually or with mechanical aids. Target tissues may include muscles, tendons, ligaments, skin, joints, or other connective tissue, as well as lymphatic vessels, or organs of the gastrointestinal system. Massage can be applied with the hands, fingers, elbows, knees, forearm, and feet. There are over eighty different recognized massage modalities. The most cited reasons for introducing massage as therapy have been client demand and perceived clinical effectiveness. In professional settings massage involves the client being treated while lying on a massage table, sitting in a massage chair, or lying on a mat on the floor. The massage subject may be fully or partly unclothed. Parts of the body may be covered with towels or sheets.