In real estate practice, depreciation means the loss of value of real property brought about by age, physical deterioration, or functional or economic obsolescence. For the meaning of depreciation in income taxation, refer to the following sections: Additional First-Year Depreciation Allowance, ACR System, ADR System, Component Depreciation, Declining Balance Depreciation, Salvage Value, Straight Line Depreciation and Sum of the Years-Digits Depreciation.