In software engineering, the term data model is used in two related senses. In the sense covered by this article, it is a description of the objects represented by a computer system together with their properties and relationships; these are typically "real world" objects such as products, suppliers, customers, and orders. In the second sense, covered by the article database model, it means a collection of concepts and rules used in defining data models: for example the relational model uses relations and tuples, while the network model uses records, sets, and fields.
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Bill Kent, in his 1978 book Data and Reality[11] compared a data model to a map of a territory, emphasizing that in the real world, "highways are not painted red, rivers don't have county lines running down the middle, and you can't see contour lines on a mountain". In contrast to other researchers who tried to create models that were mathematically clean and elegant, Kent emphasized the essential messiness of the real world, and the task of the data modeller to create order out of chaos without excessively distorting the truth.