The appraisal, technically named as report of valuation, is a document signed by  a competent professional  and is  aimed to establish in a justified way the value of a good, in accordance with some established criteria, developing a methodology adapted to the proposed purpose.

The appraisal of a good is subject to a strict legal regulation that not only establishes the criteria and methodology to realize it, but also determines who can do it. This regulation, which in Spain is constituted by a Ministerial Order dated on November 30, 1994 and issued by the Department of Economy and Estate, is a norm that establishes a concrete methodology based on a few definitions and principles that inspires its own draft.