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.
A sampling of terms defined includes: active premium, aggregation, angel financing, asset allocation, backwardation, benchmark, bridge loan, capital structure arbitrage, coefficient of determination, commodity option, convertible arbitrage, deferred futures, discretionary trading, distressed debt, enumerated agricultural commodities, extrinsic value, follow-on funding, hedge ratio, interdelivery spread, long short equity, modified value-at-risk, offshore fund, piggyback registration, social entrepreneurship, systematic trading, tracking error, underlying futures contract, venture capital method, and weather premium.
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).