Net national product (NNP) refers to gross national product (GNP), i.e. the total market value of all final goods and services produced by the factors of production of a country or other polity during a given time period, minus depreciation. Similarly, net domestic product (NDP) corresponds to gross domestic product (GDP) minus depreciation. Depreciation describes the devaluation of fixed capital through wear and tear associated with its use in productive activities.