The process of finding out the value of the property on the highest property value is called real estate appraisal or property valuation.
Real estate appraiser does the job of finding the fair market value.
Real estate appraisal gives value to the property for different purposes like assigning 2 values for one property. in this case improved value and vacant value may be both given to a property located in residential or commercial zone. But keep in mind that this is not the real value and should not be used for evaluating.
Real estate appraisal may be done by a real estate investor and the value of the property will be based on how much he bought the property and sell it at a much higher price or he could do it based on the expected value of his property in 3-6 years time and the amount of money to increase the value for example, repainting a room or the roof of the house.