Environmental science is an important and special aspect of today's educational system because it takes parts in almost all of the processes of the universe especially our planet earth. The study of environmental science helps toward understanding of how and why and plays an important role in the moulding of this industrialized and urbanized world. As we all know that today we are living in a very complex world with complex legal and political issues surrounding the environment. To assure an adequate supply of environmental natural resources to meet broad needs of humans around the world, the development of scientifically sound strategies for sustainable environment development are critical. The main aim behind this book is to make every one aware about the ongoing issues of environment (our surroundings) and to preserve the quality of environment that nourishes both the humans and other natural communities. To better understand these issues, one also needs to know the essentials of environmental science and it is only possible through a proper reference.