Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In computer science, an X-tree is an index tree structure based on the R-tree used for storing data in many dimensions. It differs from R-trees, R+ trees and R trees because it emphasizes prevention of overlap in the bounding boxes. In cases where nodes cannot be split without preventing overlap, the node split will be deferred, resulting in super-nodes. In extreme cases, the tree will linearize, which defends against worst-case behaviors observed in some other data structures.