2.2. What a Data Warehouse Is
Bill Inmon is an American computer scientist and is recognized by many as the father of the data warehouse concept. His definition of a data warehouse is widely accepted.2 A data warehouse is a subject-oriented, integrated, time-variant, nonvolatile collection of data in support of management’s decisions.
“Subject oriented” means that the collected data are related to a specific business area—for example, a sales and marketing department. However, in practice, the data warehouse can include different business areas. The data warehouse is restricted to one business area or even to one department, usually called a data mart, which is a local warehouse that is generally a part of a corporate warehouse.