Appraisals
Because much private, corporate, and public wealth lies in real estate, the determination of its value is essential to the economic well-being of society. An appraisal is not a guarantee of condition. An appraisal is used to determine the market value or fair market value of a property.

What is an appraisal?
A home appraisal is quite simple. The physical inspection of the property being appraised can take from fifteen minutes to several hours, depending upon the size and complexity of the property. An appraiser walks through the house to count the rooms and get an idea of the general condition. The appraiser will ask about any problems found, and will try to gauge any impact on value attributable to those problems.
After the initial inspection of the property, the appraiser will spend time touring the neighborhood and researching the area. The purpose of this tour is to search for comparable sales that have sold within the last year or so. When the fieldwork is finished, the appraiser completes the report at his office. The report can range from short (typically under ten pages) to a long narrative that can sometimes exceed a hundred pages.
Your lender must provide you with a copy of the appraisal report upon your written request. If you are dissatisfied with any information contained in your appraisal report, you should contact your lender immediately.
Appraisers
It is the job of the professional appraiser to determine these values by gathering, analyzing, and applying information pertinent to a property.
Many states require all real estate appraisers to be, at a minimum, state licensed or state certified and have fulfilled rigorous education and experience requirements. They must adhere to strict industry standards and a professional code of ethics declared by the Appraisal Foundation.
-- Tips courtesy of HomeAdvisor.com