A hierarchical database is a type of database that organizes data in a tree-like structure, where each record has a single parent and can have multiple children. This model resembles a family tree, with the top-level record known as the root, and all other records branching out from it. Each child record can only have one parent, which helps maintain a clear and organized relationship between data. In a hierarchical database, data is accessed through a series of parent-child relationships, making it efficient for certain types of queries. Common examples of hierarchical databases include IBM's Information Management System (IMS) and Windows Registry. However, this structure can be limiting, as it does not easily accommodate many-to-many relationships.