This book provides the essential information necessary for students and scientists in the life and health sciences and chemistry of biologically active substances. The book adopts a readable, friendly style that helps introduce the reader to this fascinating and exciting world of hormones. This book is devoted to highlight the recent progress on the extraction, analysis, physico-chemical properties and the use of hormones. Much attention is paid in several chapters to steroid hormones, which play an important role in human biochemistry. Information on phytohormones and hormones in mushrooms is also original. The book presents revolutionary results in clinical trials of hormones, comparative genomic analysis, and the use of these substances as a tool for biosynthesis. The logic of the whole book is subordinated to the scheme "presence in living organisms -- identification and analysis -- properties -- application and safety" of hormones. It also includes some of the vital pieces of work being conducted across the world on various topics related to the study of biologically active substances. Through it, we attempt to further enlighten the readers about the new concepts in this field. Altogether, presented in an organized, concise, and simple-to-use format, "A Closer Look at Hormones" allows quick access to the most frequently used data.