This book discusses the topic of water stress and provides information regarding its impact on biodiversity. Ever since the Earth was formed, the amount of water present on our planet has remained consistent for about 4 billion years. From there on, it has cycled through evaporation, condensation, precipitation and surface runoff multiple times till date. Water scarcity as an abiotic factor ranging from moderate to severe stress levels, along with loss of moisture in the soil, is an extremely difficult situation for most organisms to comply with, especially terrestrial plants and their food-chain dependents. Due to the possibilities of increasing temporary or even permanent, drought conditions in the future, there is immense emphasis on enhancing plant resistance against drought and enhancing yield performance in water-limited environments through genotype selection in important crops. Comprehension regarding the reactions of plants and organisms to water stress conditions has also been encompassed in this all-inclusive book along with discussions on survival strategies adopted under varied moisture levels.