The core structure of a steroid comprises of seventeen carbon atoms, bonded in four fused rings. These include one five-member cyclopentane ring, and three six-member cyclohexane rings. Steroids are biologically active organic compounds which have four rings arranged in a specific molecular configuration. These are found in several animals, fungi and plants. They are usually formed in the cells from the sterols lanosterol or cycloartenol. Steroids can be modified by slight changes to the ring structure. Gonane is the simplest steroid, which is the fundamental nucleus of all steroids. It consists of the fusion of a phenanthrene ring with a cyclopentane ring. This book brings forth some of the most innovative concepts and elucidates the unexplored aspects of steroids. It is a valuable compilation of topics, ranging from the basic to the most complex advancements in the research of steroids. The book is appropriate for students seeking detailed information in this area as well as for experts.