Bridging the gap between the database and signal processing communities, this text provides the necessary background information for the reader and presents along intuition and mechanics of the best existing tools in each area. The first half of the text reviews the most successful database access methods, in increasing complexity, reaching up to spatial access methods and text retrieval. In all cases, the emphasis is on practical approaches that have been incorporated in commercial systems, or that seem very promising. The second half uses the above access methods to achieve fast searching in a database of signals. A general methodology is presented, which suggests extracting good features from each multimedia object, thus mapping objects into points in a metric space. Finally, the book concludes by presenting some recent successful applications of the methodology on time series and color images. This work is targeted towards researchers and developers of multimedia systems and can also serve as a textbook for a graduate course on multimedia searching, covering both access methods as well as the basics of signal processing.