"AB" can refer to various concepts, but one common meaning is "A/B testing." This is a method used in marketing and product development to compare two versions of a webpage, app, or advertisement. By showing different versions to different users, companies can determine which one performs better based on user engagement or conversion rates. This helps businesses make data-driven decisions to improve their offerings. Another interpretation of "AB" is "AB blood type," which is one of the four main blood types in the ABO blood group system. People with AB blood have both A and B antigens on their red blood cells, making them universal recipients for blood transfusions. Understanding blood types is crucial in medicine, especially during surgeries or emergencies.