Ageing has become a great problem for many countries. Due to world-wide life prolongation, the number of people over 60 years old has grown rapidly into a ten percent piece of the world population. The growing age of the world population raises many social, economical, and medical problems. The proportion of people in the economically active age groups to those who are over 65 is constantly decreasing. A major consequence of the increasing numbers of individuals in advanced age groups is increasing numbers of patients suffering from age-related diseases. The aim of this book is to present the basic data on human ageing as well as on age-related diseases.