Brake fluid is a specialized hydraulic fluid used in the braking systems of vehicles. It transfers force from the brake pedal to the brake components, allowing the vehicle to slow down or stop effectively. Brake fluid is designed to withstand high temperatures and pressures, ensuring reliable performance under various driving conditions. There are different types of brake fluid, including DOT 3, DOT 4, and DOT 5, each with specific properties and applications. It's essential to regularly check and replace brake fluid to maintain optimal braking performance and prevent issues like brake fade or system corrosion.