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.
On the other hand, commodity option buyers are exposed to limited risk and unlimited profit potential, but they also face dismal odds of success on each individual speculation. For this reason, we often refer to the practice of buying options in the commodity markets as the purchase of a lottery ticket. It probably won’t pay off but if it does the potential gain is considerable. Conversely to the commodity option seller, an option buyer views the position as an asset (not a liability) until it is sold or expires. This is because any long option held in a commodity trading account has the potential to provide a return to the trader, even if that potential is small.
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).