There have been extraordinary changes in medicine since the start of the 20th Century. Diseases that were killers in 1900, such as polio, have been almost wiped out. Hundreds of new drugs have been developed. This book shows how today's extraordinary surgical techniques, such as heart transplants, would have been unthinkable for a doctor a hundred years ago. And, unlike 1900, people in many countries today can see a doctor or other healthcare worker when they need to, often for free.