1-It is good and important for each one to know his/her blood type, because life full of risks and accidents, so as when some one get injured from a situation, if he/she still conscious he/she will...
They are important because not all blood types mix. A blood infusuion from the wrong group may do more harm than good.
The presence of A and or B antigens.
In case any of you need an emergency blood transfer.