The different blood types and what they mean

By Max. D Gray. Updated: January 16, 2017
The different blood types and what they mean

All blood is composed of the same components, but not all people have the same blood type of this vital fluid. Blood type depends on two factors: the blood group based on antigens and the Rh system, which can be positive or negative. Based on this, the eight blood types can be determined. This is of vital importance for blood transfusions because not all blood types are compatible with each other. In this article at we'll describe in detail about the different blood types and what they mean.


To understand the different blood types, you need to understand what causes them. First, it's important to understand the existence of different antigens , substances that are able to create an antibody, that may be considered foreign or aggressive. So if a person has an antigen in their red blood cells, the blood plasma contains an antibody against a different antigen. Based on this, the system was created with groups A, B and 0 based on the types of antigens.

A, B and 0 blood groups

To make it easier: those with A antigens in their blood cells have B antibodies. So that A types can only accept other A types and reject all B antigens (due to the antibodies). Conversely it happens with B rejecting all A antigens. While those with both A and B antigens, have no antibodies in their blood plasma. The opposite occurs for those who have type 0, who have antigens in their red blood cells but have both A and B anti-bodies in their blood plasma.

The table shows all of the combinations of antigens and antibodies.

The different blood types and what they mean - A, B and 0 blood groups

Rh factor

In addition to blood group, the blood type also influences the Rh factor (Rhesus) or D antigen. This is the antigen that determines a positive or negative value to the blood group and when this antigen is present in red blood cells, it's designated as positive and if not, then it's negative. Thus, the eight blood types are: A / A-. B / B-. AB / AB-. 0 / 0-.

Blood compatibility

As noted at the beginning, blood types are important for donating blood and blood transfusions, since not all of them are compatible. Be aware of the following:

  • 0- are the only universal donors, i.e. they can give blood to any blood group.
  • AB are universal recipients and can receive all blood types.

The table shows the different combinations that can be made between donors and recipients when donating blood.

The different blood types and what they mean - Blood compatibility

This article is merely informative, oneHOWTO does not have the authority to prescribe any medical treatments or create a diagnosis. We invite you to visit your doctor if you have any type of condition or pain.

If you want to read similar articles to The different blood types and what they mean, we recommend you visit our Diseases & secondary effects category.

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1 comment
Abdulkadir Tijjani
In which finger you prick to make a test on identify blood group?
OneHowTo Editor
It's usually the index finger
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