Call
A contract giving its holder the right, but not the obligation, to buy the underlying at the strike, on or before expiration depending on the exercise style.
The buyer of a call pays a premium for the right to buy the underlying at the strike. The seller collects that premium and takes on the obligation to deliver the shares if the call is exercised.
A call gains intrinsic value as the underlying rises above the strike, and the buyer’s maximum loss is the premium paid. American-style equity options can be exercised on any business day up to and including the expiration date, while index options are generally European-style and can be exercised only at expiration.
Illustrative example (hypothetical numbers, not a real trade): a $100 strike call costs $4.00, or $400 per contract. If the stock is at $110 at expiration, the call is worth $10.00, or $1,000. If the stock is at or below $100, the call expires worthless and the buyer loses the $400 paid.