Lands surfaces submitted to salt stress are increasing day by day in arid, semiarid regions and especially in the Mediterranean area. Nearly 40% of world's surface has salinity problems. At present, out of 1.5 billion hectares of cultivated land around the world, about 77 million hectares (5%) is affected by excess salt content. Salt stress is an abiotic stress that can affect the plant growth and physiological and biochemical activities such as photosynthesis activity and chlorophyll content. Decades of research have been devoted to understand the physiological mechanisms underlying the ability of plants to tolerate abiotic stress, in particularly, salinity and drought stresses. Ion distribution is one of different strategies commonly used by plants to improve salt stress tolerance. This book provides a physiological mechanism based upon various indices involved in cotton salt tolerance. Thereby, the book is recommended to all those who are interested in plant salt tolerance.