B blood is one of the four main blood types in the ABO blood group system, which also includes A, AB, and O. People with B 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 other B type donors and O type donors, but not from A or AB type donors. The B blood type is further classified into two subtypes: B positive and B negative, depending on the presence of the Rh factor. Approximately 10% of the global population has B blood, making it less common than A and O types. Understanding blood types is crucial for safe blood transfusions and organ transplants.