As one of the functional fluids on a moving vehicle,a brake fluid has many different functions to fulfill in order to have control over the movement of the vehicle.Over the years,this control system has evolved signifi-cantly from nothing more than a block of wood into a system with high-end sensitive technology.As soon as the braking system became hydraulic,the need for specifications and increasing quality requirements became apparent.Much like the hydraulic liquids in aviation,brake fluids are a very important safety aspect in their application.Therefore,it is important to develop a much better understanding of brake fluids and their per-formance characteristics and requirements.This report intends to provide a detailed insight into the development of braking system and the origin of brake fluids but more so into the performance needs and quality differences of todays brake fluid types and grades.It is intended as an aid to create a better understanding and knowledge of a fluid that is usually taken for granted.