And it really does save lives . It's got everything - oxygen, nutrients, antibodies. You would be dead without it. Just like a car needs petrol and oil to make it go, the body needs blood to make it work. They do it at places like the Red Cross.
Most adults have about four litres of blood.
Donors have to fill in forms, to check if they are well enough to donate, and if they might have done anything that could have infected their blood and therefore make it dangerous to pass on. Then, after the forms, there's a confidential, private interview, to double-check that everything's okay. There are a lot of forms because we want quite a lot of information about the donor. It doesn't hurt a bit, and after about ten minutes, it's all over. Firstly the blood is put in a centrifuge, and whizzed around really quickly.