Tree structures refer to a type of data structure used in computer science to organize and store data in a hierarchical manner. The structure consists of nodes, with each node having a parent node and zero or more child nodes. The topmost node in the tree is called the root node. Tree structures are commonly used in various applications such as computer algorithms, databases, and file systems. They provide an efficient way to represent relationships between data elements and allow for quick access and manipulation of the stored information. Some common types of tree structures include binary trees, binary search trees, and B-trees. These structures play a critical role in many computer science algorithms and are essential for efficiently organizing and accessing large amounts of data.