An American-style option is an option which can be exercised before expiration, subject to the contract and broker deadlines. This differs from European-style options, which permit exercise at expiration. With otherwise identical terms, the additional exercise right cannot reduce theoretical option value. U.S. listed equity options are generally American-style; verify the specific product rather than assuming this applies to every stock option worldwide.
Selling an option to close is different from exercising it. Exercise style refers to contractual rights, not the country where the option trades. Actual market quotes can also differ because of liquidity and other terms.
