Most property insurance policies contain an appraisal provision. When invoked correctly, each side selects an appraiser. The two appraisers review the damage, estimates, documentation, and disputed items. If the appraisers cannot agree, an umpire may be selected to help resolve the disagreement.
The final appraisal award can become binding as to the amount of loss, depending on the policy language and applicable circumstances.
In plain English: appraisal is about getting the number resolved when the claim value is disputed.