Real estate appraisal, property valuation or land valuation is the practice of developing an opinion of the value of real property, usually its Market Value. The need for appraisals arises from the heterogeneous nature of property as an investment class: no two properties are identical, and all properties differ from each other in their location which is one of the most important determinants of their value. For mortgage valuations of improved residential property in the US, the appraisal is most often reported on a standardized form, such as the Uniform Residential Appraisal Report.