The book covers the principles, techniques, and standards for online GIS. This new edition covers the most recent major advances in the metadata arena. The semantic web (Web 2.0) is now well developed. GPS has also advanced in terms of the availability of location-based services, which rely on metadata and online services. In this new edition, all chapters are significantly revised and updated. Three new chapters are included to cover spatial data mining, location-based services, and new technologies.