Hierarchical data structures organize data in a tree-like format, where each element, known as a node, has a parent-child relationship. The topmost node is called the root, and it branches out to various child nodes, which can further have their own children. This structure is useful for representing relationships that have a clear hierarchy, such as organizational charts or file systems. Common examples of hierarchical data structures include binary trees, XML documents, and directory structures. These structures allow for efficient data retrieval and management, as they enable quick navigation through levels of data. Hierarchical data is often used in databases and programming to model complex relationships.