The book is the first thorough overview of the first important steps to develop a worldwide virtual observatory so that, in the future, it could be easier to "dial-up" a part of the sky than wait many months to access a telescope. The articles in this book present details on the status of the first efforts to develop a standardized framework for the virtual observatory, including steps towards completion and deployment of technical infrastructure, uptake by data providers worldwide, and utilization by the scientific community.