This tutorial provides a comprehensive and comparative overview of general techniques to efficiently support similarity queries in spatial, temporal, spatio-temporal, and multimedia databases. In particular, it identifies the most generic query types and discusses general algorithmic methods to answer such queries efficiently. In addition, the tutorial sketches important applications of the introduced methods, and presents sample implementations of the general approaches within each of the aforementioned database types. The intended audience of this tutorial ranges from novice researchers to advanced experts as well as practitioners from any application domain dealing with spatial, temporal, spatiotemporal, and/or multimedia data.