The book is dedicated to the world of the forest - so dear and at the same time so little familiar to us. The author, a famous scientist and popularizer of science B. F. Sergeev, talks about various forest communities and their numerous inhabitants from the point of view of ecological physiology - a science that studies the processes of adaptation of individual creatures to life in a certain natural environment. After reading this book, you will learn a lot of new things and interesting things about the life of forests growing in different climatic conditions: deciduous forests of the temperate zone, evergreen Siberian taiga, tropical jungle. And perhaps you will fall in love with the inhabitants of the forest wilds even more. For teachers, middle and high school students and a wide range of nature lovers.