Muscle contraction is a vital biological activity. In three centuries of scientific pursuit since Leeuwenhoek and Croone observed the cellular structure of striated muscles, the knowledge gained from extensive studies has formed a detailed understanding of muscle function at the molecular and atomic level. Contractions of vertebrate skeletal and cardiac muscles are controlled by Ca2+ signalling through the troponin complex in the sarcomeres, which are contractile machinery consisting of interactive myofilaments. Since the discovery and biochemical characterisation of troponin and its three subunit proteins over four decades ago, intensive research from protein structure and genetic diversity to post-translational modification and pathological mutations have comprehensively established the molecular structure of troponin and the mechanistic details of its function in the regulation of muscle contractions. The advanced knowledge from troponin research has contributed significantly to the current understanding of cardiac and skeletal muscle function in health and diseases. It is a timely necessity to comprehensively, yet concisely, summarise the current knowledge and look toward the future direction of troponin research. Contributions to this book have been made by leading experts in troponin studies, and its contents include chapters that describe milestone discoveries and recent research advances. This wonderful collection provides a unique reference for students and research investigators who have an interest in muscles, protein structure-function relationships and molecular evolution, as well as cardiac function and myopathies. Readers will not only obtain an in-depth state-of-the-science understanding of troponin structure and function, they will also be exposed to visions that will lead them toward future investigations and the advancement of troponin research.