This book provides a comprehensive text that discusses Metaverse from a technological perspective with a wide range of topics from the basic to advanced levels focusing on how state-of-the-art technologies can be adopted for Metaverse. It begins with an overview including architecture, main components, devices, benefits, and typical applications. Then it discusses how the essential technologies, e.g., AI, computer vision, Virtual Reality (VR), Augmented Reality (AR), Extended Reality (XR), blockchain, and edge computing, can be utilized for developing Metaverse applications. Finally, the book describes important issues and challenges (e.g., security, computing, communications and networking, data collection, ethics, human health, privacy, and social impact) in implementing Metaverse applications.