Nowadays, a significant number of applications require the organization of data elements that contain at least one spatial attribute. R-trees have a simplicity of structure and, together with their resemblance to the B-tree, allow developers to incorporate them easily into existing database management systems for the support of spatial query processing. This book provides an extensive survey of the R-tree evolution, studying the applicability of the structure and its variations to efficient query processing, accurate proposed cost models, and implementation issues like concurrency control and parallelism.