Brake flui is a type of hydraulic fluid used in hydraulic brake applications in motorcycles, automobiles, light trucks, and some advanced bicycles. It is used to transfer force under pressure from where it is created through hydraulic lines to the braking mechanism near the wheels. It works because liquids are not appreciably compressible. Braking applications produce a lot of heat, so brake fluid must have a high boiling point to remain effective, and must also not freeze under normal temperatures. These requirements eliminate most water-based solutions.