"The Uniform Standards of Professional Appraisal Practice (USPAP) is...
...the generally recognized ethical and performance standards for the appraisal profession in the United States. USPAP was adopted by Congress in 1989, and contains standards for all types of appraisal services, including real estate, personal property, business and mass appraisal. Compliance is required for state-licensed and state-certified appraisers involved in federally-related real estate transactions. USPAP is updated every two years so that appraisers have the information they need to deliver unbiased and thoughtful opinions of value.
To become a real property appraiser in the United States, appraisers must take the 15-Hour National USPAP Course (or its equivalent). Additionally, real property appraisers must take the 7-Hour National USPAP Update Course (or its equivalent) once every two calendar years."
-- The Appraisal Foundation