Under Section 54 of the Transfer of Property Act, 1882, "sale" is defined as:

Section 54 of TPA, 1882 defines "sale" as the transfer of ownership in exchange for a price paid or promised or part-paid and part-promised. The consideration for a sale must always be a price (money), distinguishing it from exchange or gift. Section 54 further provides the mode of completion: for tangible immovable property of a value of ₹100 or upwards, or a reversion or other intangible thing, sale can only be made by a registered instrument; for tangible immovable property of a value less than ₹100, sale may be made either by a registered instrument or by delivery of the property. The definition specifically includes part-paid and part-promised consideration, recognising installment-based purchases. The transferor is called the "seller" and the transferee the "buyer."