AB+ is a blood type in the ABO blood group system, characterized by the presence of both A and B antigens on the surface of red blood cells. It is one of the four main blood types, which also include A, B, and O. Individuals with AB+ blood can receive blood from all other blood types, making them universal recipients. The "+" in AB+ indicates the presence of the Rh factor, a protein that can be present on red blood cells. This means that AB+ individuals can receive blood from both Rh-positive and Rh-negative donors. AB+ blood is relatively rare, found in about 4% of the global population.