We need to make sure that we have enough supplies of all blood groups and blood types to treat all types of conditions.
By giving blood, every donor helps us meet the challenge of providing life-saving products whenever and wherever they are needed.
We need to maintain a regular supply of all blood groups and types so we can provide it to the hospitals and patients who need it.
Some rare sub-types are more common in specific communities, which is why we particularly need more black donors and are always looking for more blood donors from black, Asian and minority ethnic communities.
We sometimes need to target specific blood types to increase stock levels. That's why we sometimes contact regular donors with the particular blood type we need, and ask them to give blood.
We are indebted to our regular blood donors for their role in helping us to save lives.
A rare blood type is any blood type that is difficult to find in the population where you may need that "rare" type of blood.
O Rh negative blood is rare but essential because it is the only blood type that can be given to anyone, regardless of their blood type.
Donors with the blood group B Rh positive are more often found in black and south Asian minority ethnic communities.
Your blood's main components are red cells, plasma and platelets. These are used to treat many different illnesses and conditions.
They have a short shelf life, so we always need to top up the supply: