There are four basic blood types.
  • A
  • B
  • AB
  • O
And their basic relationships are as follows:
  1. Donating

    • Type A can donate to A or AB
    • Type B can donate to B or AB
    • Type AB can donate to AB only
    • Type O can donate to anyone
  2. Receiving
    • A can receive from A or O
    • B can receive from B or O
    • Type AB can receive from anyone
    • O can only receive from O

There is also an Rh factor attached to a blood type which is the + or -. The plus means there is protein present in your blood. A minus denotes a lack of protein. A person with a negative Rh factor can only receive negative type blood. Otherwise, there is a chemical interaction that could cause clumping, a stroke, and possibly death.