The fruit of many years experience on the creation of synthetic worlds and virtual realities, this book is based on the considerable expertise of the authors, who share their knowledge of mastering the complexities behind the creation of Virtual Reality (VR) applications. The first part of the book reviews the basic theoretical and practical concepts involved in the visual aspect of virtual environments. Part 2 provides more details on the components, structure and types of virtual worlds that can be created, including detailed explanations of the main modeling and animation techniques for virtual characters - one of the most important aspects in a virtual world. A review and discussion of the main types of VR system architectures defines the different alternatives for organizing and designing a VR application. The final part covers the main principles of Virtual Reality hardware using a generic classification of interaction devices based on a human-centered approach (via the five human senses: vision, sound, touch, smell and taste). The book closes with an overview of successful VR systems and applications and gives a glimpse of what lies in the future. This book was conceived as a guided tour and provides practical explanations of each step in the process of creating a Virtual Reality application. It can be used both as textbook for a Virtual Reality course, and as a reference for courses covering computer graphics, computer animation or human-computer interaction topics.