Blood types/group introduction: There are four main blood groups (types of blood): A, B, AB and O. Your blood group is always inherit from the parents genes.
A blood type (also called a blood group) is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells.
How blood type scanner works? it's easy all you have to do is to put any of your fingers on the scanning area, wait the analyzing process to finish and there you are your blood group will show in the results screen.
Disclaimer : Always remember Best Blood Type scanner is about pranking, and any results you see is just for fun, also tell you friend and family that its fake too.