A collection, either digital or physical, of all the products an organization sells.
The goal of the product hierarchy is to represent the catalog by grouping products together logically in a way that allows users to find products. Before the internet era paper catalogs were commonly used by organizations to list all their products. Digital catalogs often are PDF versions of the paper catalogs. The catalog is used to inform the design of the product hierarchy as it contains product groupings that users will be familiar with.