The book has been organized into seven chapters. The first explains the concept of web and Webometrics. Describes the webometric tools and various statistical analysis methods. The second chapter brings out the review of literature on the concepts and dimensions of webometric tools and techniques. Chapter 3 provides a brief account of the websites of Astronomy and Astrophysics libraries in India and the global level. The data analysis and interpretation on the websites of Astronomy and Astrophysics Libraries covering weblink structure analysis, Web Impact Factor, Link network analysis, WISER, Google Page Rank and Alexa Page Rank and performance and accessibility of websites and other webometric tools and techniques were presented in Chapters 4, 5 and 6. The last chapter is summary of the findings, conclusions and the outcome of the research.