There are many steps along the process of buying a home. If you are financing your home purchase an appraisal is one of those steps. An appraiser is hired by the lender to independently verify the value of the home you are looking to purchase. The lender wants to insure that the money they will be lending is justified based on the condition of the home and recent sales in the area.
If you want to learn more about this process check out these links from Realtor.com and QuickenLoans.
