The hydraulic braking system is the single most widely used means of bringing a road vehicle to a controlled stop, and an understanding of how it works is fundamental to automotive and mechanical engineering education. This paper presents a structured review of hydraulic braking systems intended for engineering diploma and undergraduate readers who are encountering the subject for the first time. The discussion begins with the historical development of braking technology and proceeds through the fluid-mechanics fundamentals — chiefly Pascal's Law — that make hydraulic force transmission possible. The major components of a typical automotive hydraulic brake circuit are described individually, followed by a step-by-step explanation of how the system works when a driver presses the brake pedal and how pressure is distributed around the hydraulic circuit. The paper classifies hydraulic braking systems by brake type (disc and drum) and by circuit layout (single and dual circuit), and it sets out the principal advantages and disadvantages of hydraulic operation relative to purely mechanical and pneumatic alternatives. Maintenance practice, common failure modes, and troubleshooting logic are covered in practical detail, and recent technological developments — including anti-lock braking, electronic brake-force distribution, and early brake-by-wire concepts — are reviewed. The paper closes with a discussion of environmental and safety considerations and the likely future direction of braking technology. Throughout, the aim has been to keep the explanation accessible and self-contained while preserving technical accuracy suitable for engineering coursework and project reference.

Key Words: Hydraulic braking system, Pascal's Law, master cylinder, wheel cylinder, disc brake, drum brake, brake fluid, anti-lock braking system, brake circuit, automotive safety.