Search computing, which has evolved from service computing, focuses on building the answers to complex search queries by interacting with a constellation of cooperating search services, using the ranking and joining of results as the dominant factors for service composition. The field is multi-disciplinary in nature and takes advantage of contributions from other research areas such as knowledge representation, human-computer interfaces, psychology, sociology, economics, and legal sciences. This book, the second in the Search Computing series, describes the evolution of theories, technologies, and methods related to search computing. The book has been divided into eight parts, reflecting the main research directions within the Search Computing project. The parts focus on: search as an information exploration task; interaction design issues when dealing with multi-domain search results; modeling and semantic description of search services; the rank-join problem; query processing techniques and architectures; tools and mashups for application development; the application of search computing to bio-informatics; and the exploitation potentials of project results.