A Hierarchical Database System organizes data in a tree-like structure, where each record has a single parent and can have multiple children. This model allows for a clear, organized way to represent relationships, making it easy to navigate through the data. Each level of the hierarchy represents a different category, with the top level being the root. In this system, data is accessed through a series of parent-child relationships, which can simplify data retrieval. However, it can be inflexible, as adding new data types may require restructuring the entire hierarchy. Examples of hierarchical databases include IBM's Information Management System (IMS) and Windows Registry.