A put or put option is a contract between two parties to exchange an asset (the underlying), at a specified price (the strike), by a predetermined date (the expiry or maturity). One party, the buyer of the put, has the right, but not an obligation, to re-sell the asset at the strike price by the future date, while the other party, the seller of the put, has the obligation to repurchase the asset at the strike price if the buyer exercises the option.
