The **brake lights** are essential to indicate that a vehicle is slowing down or stopping. These lights must be **intense red** in color and are located at the rear of the vehicle. Their function is to alert drivers coming from behind that the vehicle is braking, which is crucial to avoid collisions.

Additionally, there is a **third brake light** which is also red and lights up simultaneously with the main brake lights. This additional light is placed above the other brake lights and is optional for cars.

On the other hand, the **reverse lights** are **white** and are used to indicate that the vehicle is going to move backward, which clearly differentiates them from the brake lights.

In summary, brake lights must be **red** to fulfill their warning and safety function on the road.