This book provides an overview of the most common techniques and methods employed in wireless fields. Conversely, it delves into a detailed study of millimeter-wave (mm-wave) and terahertz (THz) systems, with a focus on various schemes for transmitting and receiving electromagnetic waves. The title comprehensively reviews key elements associated with wireless communications, emphasizing the generation and detection of mm and THz waves. It explores specifications, innovations in new materials for high-speed terahertz and millimeter-wave technology, and considerations related to components and system aspects. Additionally, the book explores the integration of machine learning (ML) and artificial intelligence (AI) in smart communication systems, along with potential applications for advanced wireless communications. Furthermore, it concentrates on recent advances and diverse research prospects in Next-Generation Wireless Communication Technologies. The book also seeks theoretical, methodological, well-established, and validated empirical work addressing these various topics.