Just as you can buy a stock because you think the price will go up or short a stock when you think its price is going to drop, an option allows you to bet on which direction you think the price of a stock will go. But instead of buying or shorting the asset outright, when you buy an option you’re buying a contract that allows — but doesn’t obligate — you to do a number of things, including:

The market value of that home may have doubled to $800,000. But because the down payment locked in a pre-determined price, the buyer pays $400,000. Now, in an alternate scenario, say the zoning approval doesn’t come through until year four. This is one year past the expiration of this option. Now the home buyer must pay the market price because the contract has expired. In either case, the developer keeps the original $20,000 collected.

Options belong to the larger group of securities known as derivatives. A derivative's price is dependent on or derived from the price of something else. As an example, wine is a derivative of grapes ketchup is a derivative of tomatoes, and a stock option is a derivative of a stock. Options are derivatives of financial securities—their value depends on the price of some other asset. Examples of derivatives include calls, puts, futures, forwards, swaps, and mortgage-backed securities, among others.

The Problem arises if one party fails to perform. The trader may fail to sell if the prices of steel goes very high like for example INR 40,000 in January 2017, in that case, he may not be able to sell at INR 31,000. On the other hand, if the buyer goes bankrupt or if the price of steel in January 2017 goes down to INR 20,000 there is an incentive to default. In other words, whichever way the price moves, both the buyer and seller have an incentive to default.
When buying or selling options, the investor or trader has the right to exercise that option at any point up until the expiration date - so simply buying or selling an option doesn't mean you actually have to exercise it at the buy/sell point. Because of this system, options are considered derivative securities - which means their price is derived from something else (in this case, from the value of assets like the market, securities or other underlying instruments). For this reason, options are often considered less risky than stocks (if used correctly).