in a hierarchical model, data is organized into a tree-like structure, implying a single parent for each record. a sort field keeps sibling records in a particular order. hierarchical structures were widely used in the early mainframe database management systems, such as the information management system (ims) by ibm, and now describe the structure of xml documents. this structure allows one-to-many relationship between two types of data. this structure is very efficient to describe many relationships in the real world; recipes, table of contents, ordering of paragraphs/verses, any nested and sorted information.