Conversely, a put option is a contract that gives the investor the right to sell a certain amount of shares (again, typically 100 per contract) of a certain security or commodity at a specified price over a certain amount of time. Just like call options, a put option allows the trader the right (but not obligation) to sell a security by the contract's expiration date. 
Research is provided for informational purposes only, does not constitute advice or guidance, nor is it an endorsement or recommendation for any particular security or trading strategy. Research is provided by independent companies not affiliated with Fidelity. Please determine which security, product, or service is right for you based on your investment objectives, risk tolerance, and financial situation. Be sure to review your decisions periodically to make sure they are still consistent with your goals.
American options can be exercised at any time between the date of purchase and the expiration date. European options are different from American options in that they can only be exercised at the end of their lives on their expiration date. The distinction between American and European options has nothing to do with geography, only with early exercise. Many options on stock indexes are of the European type. Because the right to exercise early has some value, an American option typically carries a higher premium than an otherwise identical European option. This is because the early exercise feature is desirable and commands a premium.
You also can limit your exposure to risk on stock positions you already have. Let’s say you own stock in a company but are worried about short-term volatility wiping out your investment gains. To hedge against losses, you can buy a “put” option that gives you the right to sell a particular number of shares at a predetermined price. If the share price does indeed tank, the option limits your losses, and the gains from selling help offset some of the financial hurt.
Arbitrage arguments:  When the commodity has plentiful supply then the prices can be very well dictated or influenced by Arbitrage arguments. Arbitrage is basically buying in one market and simultaneously selling in another, profiting from a temporary difference. This is considered riskless profit for the investor/trader. For example, if the price of gold in delhi is INR 30,000 per 10 grams and in Mumbai gold price is INR 35,000 then arbitrageur will purchase gold in Delhi and sell in Mumbai
Options markets trade options contracts, with the smallest trading unit being one contract. Options contracts specify the trading parameters of the market, such as the type of option, the expiration or exercise date, the tick size, and the tick value. For example, the contract specifications for the ZG (Gold 100 Troy Ounce) options market are as follows:
The world of commodity options is diverse and cannot be given justice in a short article such as this. The purpose of this writing is to simply introduce the topic of options on futures. Should you want to learn commodity options trading strategies in more detail, please consider purchasing "Commodity Options" published by FT Press at

However, unless soybeans were priced at $15 per bushel in the market on the expiration date, the farmer had either gotten paid more than the prevailing market price or missed out on higher prices. If soybeans were priced at $13 per bushel at expiry, the farmer's $15 hedge would be $2 per bushel higher than the market price for a gain of $2,000,000. On the other hand, if soybeans were trading at $17 per bushel at expiry, the $15 selling price from the contract means the farmer would have missed out on an additional $2 per bushel profit.

However, for put options (right to sell), the opposite is true - with strike prices below the current share price being considered "out of the money" and vice versa. And, what's more important - any "out of the money" options (whether call or put options) are worthless at expiration (so you really want to have an "in the money" option when trading on the stock market).