A put option is an investment strategy where the investor bets the underlying asset's (stock, bond, commodity) market value will fall. The put option gives the investor THE OPTION to sell a specified amount of the underlying asset at a specified price(strike price), within a specified time.

EX: If an asset is valued at $50.00, and you expect the price to fall below that, you would purchase a call option. If the price becomes $45.00, you now have the option to execute your put option (sell the asset) at $50.00, making $5.00 per share.