A blind spot is the area that cant be seen either when using normal forward vision or when using the mirrors. The main blind spots are; (1)The area between what you see as you look forward and what you see in your exterior mirror. (2)the area obscured by the bodywork of the vehicle when you look in your mirrors. Vehicles of different shapes have different blind spots. You should be aware that some 4x4s have very large blind spots - they can obscure a group of pedestrians, a motorcyclist or a small car. Exterior mirrors help reduce blind spots, but remember that mirrors wont show you everything behind you. You can buy auxiliary mirrors to mount on the surface of your exterior mirrors. Theses give an even wider angle of vision and go some way to reducing blind spots, but wont entirely eliminate them. Even though you have used your mirrors, always look round over your right shoulder to check the blind spot before you move off.