An appraisal is basically an evaluation by an independent professional. It could an appraiser to determine an opinion of the value of the home. The appraiser will look at recent comparable sales and market conditions to determine the value of a home in order to help support the agreed upon sale price. So let’s say the house you were looking to buy is $250,000. If you’re lucky, it may appraise for higher than what you are going to pay for it and that just means you get instant equity on the day you close. Suppose however the value comes in lower than the sales price. Well, this does allow you to possibly renegotiate with the seller, which may reduce your loan amount and save you money on your monthly payments. Appraisers also look at the condition of the home. Some programs do have much more strict guidelines on condition than others.
If you have questions, let me know.