The most common blood type among humans is O positive (O+). Approximately 37% of the world's population has this blood type. O positive blood can be given to any Rh-positive blood type, making it particularly valuable in blood transfusions. It is also a universal donor for Rh-positive patients, which enhances its importance in emergency medical situations. The distribution of blood types can vary significantly by region and ethnicity, but O positive consistently remains the most prevalent worldwide.