The contract of sale is a legally binding document that you sign by you and the vendor (seller). This contract sets out the terms and conditions of the sale, as agreed to by you and the vendor. While the contract of sale becomes a legally binding document the moment you sign it, there may be a cooling-off period during which you can cancel the sale if you bought the property by private sale. This is generally negotiated before you sign the contract of sale. The cooling-off period does not apply to auctions.