Just over a century ago, a man called Karl Landsteiner discovered that blood came in different types. His work changed the face of modern medicine and allowed successful blood transfusions to become an everyday procedure in our hospitals.

Each year, World Blood Donors day is held on June 14, Landsteiner's birthday, to celebrate and recognise the contribution of millions of donors around the world who turn up to give - in the words of Tony Hancock - nearly an armful' on a regular basis.

In fact, the amount of blood given in each donation is just under a pint - considerably less than an armful - but it is enough to ensure thousands of people every week can recover from illness or surgery and get on with their lives.

There are about 1.6million regular blood donors in the UK giving 2.1million donations, but although that might sound a lot, it amounts to only five per cent of those who are actually eligible to donate giving two or three times a year.

The National Blood Service (NBS) hopes that by celebrating the achievements of those who give up their time, and their blood, to help others, it will raise awareness and more people will come forward to raise some of the 8,000 units of blood that the NBS needs to collect every day to keep up with demand.

This year's World Blood Day will also have the theme of safe blood for motherhood', highlighting the importance of safe blood for women during childbirth.

In the UK, we take it for granted that blood given during operations or transfusions will be readily available and free from disease, but in many developing countries this is not the case, and improved access to safe blood transfusions could save tens of thousands of lives every year.

The NBS hosts blood donor sessions all year round in the UK at hundreds of locations, so there is bound to be one near you.

If you are aged between 17 and 60, generally fit and healthy, and weigh more than 50kg, you could be eligible to give blood. Naturally some people will feel a bit squeamish at the thought of becoming a blood donor, but the procedure is quick and simple, and most people barely feel a thing.

Before you give blood, nurses at the donation centre will ask you a few questions to make sure it is safe for you to donate, and they will also be able to help with any queries you may have. The whole process lasts about half an hour, but the actual bit with the needle only takes about ten minutes so, before you know it, you can be relaxing with your complementary tea and biscuits knowing that you've just helped save a life.

If you would like to become a blood donor call the National Donor Helpline on 0845 7711711 or log onto www.blood.co.uk