The aim of the book is to understand mechanisms of plant responses to their environment. The book will be a literature review of plant responses to different types of environmental stresses. A focus is put on molecular mechanisms as they have allowed tremendous progress in our understanding of plant responses to stress. Responses of plants to drought, temperature stress, toxic concentrations of heavy metals, biotic stress, etc. are presented. The book also includes advances in the improvement of plant resistance to stress by genetic engineering. Scientific strategies and experimental design to study plant response to environmental pollutants and other stresses are discussed through analysis of case studies.