B型 (Blood) is one of the four main blood types in the ABO blood group system, which also includes A型, AB型, and O型. People with B型 blood have B antigens on the surface of their red blood cells and produce anti-A antibodies in their plasma. This means they can receive blood from B型 and O型 donors but cannot receive A型 or AB型 blood. B型 blood is relatively common, with varying prevalence across different populations. In some regions, it is more frequent among certain ethnic groups. Understanding blood types is crucial for safe blood transfusions and organ transplants, as compatibility can prevent serious immune reactions.