Brake fluid or brake fluid is fluid that is responsible for the transfer of hydraulic pressure from the brake pump to the brake cylinder, which eventually causes the thrust of the brake on the disc. Because of its performance, this liquid has to have minimal compressibility. The liquid should also be sensitive to the air bubble and not allow the formation of the bubble. The evaporation of the brake oil must be very small and compatible with the metal and metal parts that are in contact with them.

This liquid is a synthetic compound with most of which is composed of glycol compounds. Brake fluid is sensitive to moisture and tends to drop down by absorbing moisture from their boiling point.