This book provides a thorough examination of both traditional and emerging multiple access systems - Non-Orthogonal Multiple Access (NOMA) and Rate Splitting Multiple Access (RSMA) - essential for efficient and low-latency communication in the ecosystem of a Massive Internet of Things (Massive IoT). In particular, it discusses their potential role in enhancing 5G networks and their consideration as the standard for 6G multiple access.Geared towards postgraduate students and researchers, the book establishes the theoretical groundwork of conventional multiple access systems while delving into practical applications. Through a focus on NOMA and RSMA, it offers valuable insights into cutting-edge wireless communication research and development.