Endocrinology is a domain of biology and medicine that is concerned with the endocrine system and its diseases and hormones. It also deals with psychological activities and the behavioral activities of metabolism, growth and development, tissue function, sleep, digestion, movement and sensory perception, which are caused by hormones. The specializations within this field are behavioral endocrinology and comparative endocrinology. The endocrinal disorders are divided into three groups - endocrine gland hyposecretion, which leads to hormone deficiency, endocrine gland hypersecretion, which leads to hormone excess, and tumors of endocrine glands. Some of the common endocrine disorders are glucose homeostasis disorders, thyroid disorders, calcium homeostasis disorders, pituitary gland disorder, sex hormone disorder, etc. This book provides comprehensive insights into the field of endocrinology. It includes some of the vital pieces of work being conducted across the world, on various topics related to this domain. The book is a vital tool for all researching and studying this field.