Introduction: basic concepts, interest, nature and scope of Environmental Science and its contribution to society. Different aspects of environment: physical, ecological, socio-economic, ethical, philosophical. Major components of environment: physico-chemical, biological, and social, and their relationships with various environmental factors. Human environment and its problems: global, national, regional. Environmental challenges for sustainable development: current and future trends in population growth, environmental pollution, development in industry and agriculture, urbanization, poverty, and resource depletion.