Electrotherapy involves applying electric current to affected body parts to ease pain, swelling, and stiffness. It works by stimulating nerves and muscles. Direct current travels unidirectionally and is used to stimulate muscle contraction or facilitate wound healing. Alternating current changes direction periodically. Safety precautions for all electrotherapy modalities include avoiding contraindicated areas, ensuring equipment electrical safety, providing instructions, maintaining distances, and delivering optimal dosages to prevent burns or other injuries.