There are four main blood types A, B, AB and O in the ABO blood group system.
The first rule of mountain climbing is about being prepared for whatever comes your way. But nothing could prepare me for what came my way on the summit of Mount Ruapehu in September 2007.
Me and my mate, James Christie, had just bedded down for the night in the Dome Shelter when the truly unexpected happened. The mountain erupted. A rumble shook the hut seconds before tonnes of mud, water and rock smashed through the hut door - and onto us. James came out ok, most of our gear was buried, it was very, very cold and my legs were crushed under tonnes of immovable rock.
Lucky for us, James still had his boots and was able to head down the mountain for help, which is hard to find on the side of an erupting mountain at night. But James came through, and a rescue team was pulling me out four hours later.
They didnt hold much hope; I was closer to dead than alive. I was unconscious with severe hypothermia and my right leg was a complete mess. Well they couldnt save my leg, but they did save my life, and they couldnt have done that without blood donated by New Zealanders like you. That blood brought me back to life, and helped keep me alive through 15 operations.
The fact that enough of the right kind of blood was on hand is thanks to the New Zealand Blood Service. They work year round to make sure we all have a safe supply of blood when we need it, all with the help of hundreds of generous New Zealanders who give a little of themselves to help others. I wouldnt be here without them.
So to all my rescuers, doctors, nurses and blood donors, thanks you literally gave me my life back.
Read more about William on his website www.williampike.co.nz (external link)