Paraffin wax bath therapy involves applying molten paraffin wax at 40-44°C to body parts using various techniques. The heat from the paraffin wax increases local circulation and skin flexibility while reducing pain and stiffness, making it useful for conditions like arthritis. A paraffin wax bath unit maintains the wax at the proper temperature through a thermostat and container, and the wax must be sterilized regularly to maintain the unit and safely reuse the wax for treatments.