The huge amount of information published on the Web gave birth to dataspaces, collections of inter-connected (and sometimes structured) information sources created by autonomous users. The existence of dataspaces opens rooms for a new kind of research, with the purpose of providing meaningful access to data, regardless of its content and format, as long as it is available. This book presents a novel approach to query dataspaces, based on an architecture that decomposes data as sets of records and stores it in optimized index structures. The authors also present a query interface, where the user poses structured queries and receives tabular data in the response. To demonstrate the viability of the method, the query interface access real data crawled from the Web. For those that are willing to explore the world of information integration, it is worth taking a look inside this book.