Blood type

Blood Types
Blood is categorized as one of four types: O, A, B, and AB. Another identifier of blood type is the Rh factor indicated as either positive or negative. The Rh factor is a term for substances found on the surface of the red blood cells, and is named for the rhesus monkey, where it was originally found. Rh factors are generally only an interest in obstetrics.

Blood Compatibility
If you are ever in need of blood, not everyone can receive all types.

Your Type:	You Can Receive:
Your Type:	O-	O+	B-	B+	A-	A+	AB-	AB+
AB+
AB-
A+
A-
B+
B-
O+
O-

Type O is known as the "Universal Donor"
Type AB is known as the "Universal Recipient"

Blood Types and Personality
According to the Japanese...

Type O	You want to be a leader, and when you see something you want, you keep striving until you achieve your goal. You are a trendsetter, loyal, passionate, and self-confident. Your weaknesses include vanity and jealously and a tendency to be too competitive.
Type A	You like harmony, peace and organization. You work well with others, and are sensitive, patient and affectionate. Among your weaknesses are stubbornness and an inability to relax.
Type B	You're a rugged individualist, who's straight forward and likes to do things your own way. Creative and flexible, you adapt easily to any situation. But your insistence on being independent can sometimes go too far and become a weakness.
Type AB	Cool and controlled, you're generally well-liked and always put people at ease. You're a natural entertainer who's tactful and fair. But you're standoffish, blunt, and have difficulty making decisions.