The word "parasite" does not evoke positive emotions in anyone. Parasites are those who live at the expense of others, whether we are talking about people or pathogenic organisms. Nevertheless, the very existence of parasites excites our imagination: we are amazed by their ability to adapt to changing external conditions, their complex life cycle, their “operandi mode”, which has no analogues in the animal world.This book is in the most accessible language , using many examples, talks about what the science of parasitology does. The author acquaints the reader with a huge variety of parasitic species, tells what principles their survival strategy is based on, what consequences “cohabitation” with them turns out to be for the host organism, how they reproduce, and even ... what advantages sometimes get the one whom the parasite has chosen and uses in as our food base.We should be grateful to parasites: they took a direct part in human evolution and made an invaluable contribution to the formation of our species, says Pierre Kerner.