A put option is a stock market device which gives the owner the right, but not the obligation, to sell an asset (the underlying), at a specified price (the strike), by a predetermined expiry/maturity date, to a buyer.
Put options are most commonly used in the stock market to protect against the decline of the price of a stock below a specified price. If the price of the stock declines below the specified price of the put option, the owner of the put has the right, but not the obligation, to sell the asset at the specified price, while the seller of the put, has the obligation to purchase the asset at the strike price. This way the buyer of the put will receive at least the strike price specified, even if the asset is currently worthless.
Source:  Wikipedia.org

A put option is a stock market device which gives the owner the right, but not the obligation, to sell an asset (the underlying), at a specified price (the strike), by a predetermined expiry/maturity date, to a buyer.
Put options are most commonly used in the stock market to protect against the decline of the price of a stock below a specified price. If the price of the stock declines below the specified price of the put option, the owner of the put has the right, but not the obligation, to sell the asset at the specified price, while the seller of the put, has the obligation to purchase the asset at the strike price. This way the buyer of the put will receive at least the strike price specified, even if the asset is currently worthless.
Source:  Wikipedia.org