In addition to the fundamentals of ecology, this textbook presents the latest data on the current state of the environment, taking into account present-day realities. The condition of the natural environment is a key priority for the sustainable development of the Republic of Kazakhstan in the 21st century. It is recommended as a textbook for university students taking the "Ecology" course, which is mandatory across all faculties and fields of specialization. It will also be useful to professionals—such as ecologists and biologists—as well as educators and teachers involved in general environmental education and the training of competitive specialists for the country.