"O형" refers to a blood type known as "Type O" in the ABO blood group system. It is characterized by the absence of A and B antigens on the surface of red blood cells. People with this blood type can donate blood to any other blood type, making them universal donors, but they can only receive blood from other Type O individuals. In terms of personality traits, some cultures associate O형 with characteristics such as being outgoing, sociable, and adaptable. However, these associations are not scientifically proven and can vary widely among individuals. Blood type theories, including those related to personality, remain a topic of debate.