Real estate appraisal is the practice of developing an opinion of the value of real property, usually its Market Value. (Real estate appraisal is American usage; many other countries use the terms property valuation or land valuation.) The need for appraisals arises from the heterogenous nature of property as an investment class: no two properties are identical, and all properties differ from each other in their location - which is the most important determinant of their value. So there cannot exist a centralised Walrasian auction setting for the trading of property assets, as there exists for trade in corporate stock. The absence of a market-based pricing mechanism determines the need for an expert appraisal/valuation of real estate/property.
A real estate appraisal is performed by a licensed or certified appraiser. If the appraiser's opinion is based on Market Value, then it must also be based on the Highest and Best Use of the real property. 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.
A Uniform Residential Appraisal Report or URAR is one of the most common forms used in real estate appraisal which was created to allow for standard reporting and analysis of single family dwellings or single family dwellings with an "accessory unit". It is also suitable for a building in a planned unit development (PUD) but is not meant to be used for appraisals of manufactured homes or condos.