There are four blood types. These blood types are A, B, AB, and O. In addition, these four blood types may be either positive or negative. Generally type A goes with type A, type B with type B, and so on. However, type O blood is a universal donor, which means that any blood type can receive type O blood. Blood type AB is a universal receiver, so if a person has type AB blood they can receive either type A, B, AB, or O.