Hydraulic fluids are specialized liquids used in hydraulic systems to transmit power. They work by transferring force through the fluid, allowing machinery to operate efficiently. Common applications include construction equipment, automobiles, and industrial machinery. These fluids are designed to provide lubrication, prevent corrosion, and maintain temperature stability. They can be made from various substances, including mineral oils and synthetic compounds. Proper selection and maintenance of hydraulic fluids are essential for the longevity and performance of hydraulic systems.