Every two seconds, someone worldwide requires a blood transfusion, but less than 5% of eligible donors regularly give blood.

Blood types are determined by the ABO group and Rh factor, creating eight main types: A+, A-, B+, B-, AB+, AB-, O+, and O-.

O negative is the universal donor type suitable for all recipients, while AB positive is the universal recipient, able to receive any blood type.

Compatibility between donor and recipient blood types is crucial to avoid immune reactions, making knowledge of blood type vital for saving lives.