Real estate transactions usually involve a purchase or a sale of real property, but may also include leasing and lease-to-buy options.  The sale of real property often includes the seller's contractual relationship with a real estate broker or salesperson.  Traditionally, a seller is obligated to provide the purchaser with a number of items, including, but not limited to: the abstract of title, redated survey, proof of payment of taxes, and closing documents.  The purchaser may have to deal not only with the seller, but also with the bank from which he or she seeks to obtain a mortgage.  The lender will then specify any number of requirements, which must be met before the mortgage application will be approved and the real estate transaction ultimately closed.