The buyer of a call option has the right, but not the obligation, to buy an underlying asset at a specified “strike” price on (in the case of a "European"-style exercise) or by (in the case of an "American"-style exercise) a specified expiration date. The buyer pays the seller a “premium,” and may profit if the price of the underlying asset is at a level above the strike price plus the premium paid, by the call’s expiration date. The seller of a call option receives and keeps the premium, but may have to sell the stock if the buyer "exercises" the option.

Buyers and sellers of call options may offset their position.