This book gives readers a complete, clear, systematic, and practical understanding of the technologies that enable Grid computing. Over the last 3 years, Grid computing has been receiving much attention & funding around the world. In the UK, for example, one national e-Science Grid center and eight regional Grid centers have been established to "make the Grid infrastructure a reality" in the near future. There is a need for a book that clearly describes and explains the underlying technologies (such as Globus 2 or 3) for newcomers to the field and Grid technology coordinators.