The purpose of the book is to present karst phenomena as natural sights in a popular way, and at the same time, emphasize their importance to people and their extreme vulnerability. Through numerous photographs and schematic models, the book tries to explain scientific findings about karst processes, formation of different surface forms and cave types, as also the problems which people arise to the karst environment with their way of life. The photographs of sixty-two authors represent different types of karst and caves from almost all over the world. Karst functions the same way all over the world. People have negatively affected the environment for thousands of years, but the sheer size of today's human population leads to more conspicuous and inevitable negative environmental consequences. Pollution affects not only water quality but also caves and their fragile ecosystems. The basis for all karst protection activities is knowledge and understanding. Karst and caves are part of our environment. Even if we do not live in the karst or ever visit a cave, all people on Earth benefit from the water they provide, from their ecosystems, and from their economic values linked to tourism. The book was published with the help of the Slovenian National Commission for UNESCO.