Pneumatic systems are often used in grippers, the part of a robot that picks something up. Gas can be compressed, making the gripper more responsive and less likely to crush what it's picking up. Air muscles are simple pneumatic devices that contract by thickening, a lot like our own muscles do. Since they are mostly made of soft plastic and rubber, air muscles can be bent around curves and can even work underwater. Vacuum grippers use suction to pick up fragile things like sheets of paper or glass.
Electromagnets use electricity to pick up and release steel or iron objects.