A real estate appraisal helps to establish a property's market value–the likely sales price it would bring if offered in an open and competitive real estate market.

Lenders will require an appraisal when you ask to use a home or other real estate as security for a loan, because it wants to make sure that the property will sell for at least the amount of money it is lending.

Don't confuse a comparative market analysis, or CMA, with an appraisal. Real estate agents use CMAs to help home sellers determine a realistic asking price. Experienced agents often come very close to an appraisal price with their CMAS, but an appraiser's report is much more detailed--and is the only valuation report a bank will consider when deciding whether or not to lend the money.

Most lenders will lend a percentage of the appraisal amount.