A forex or currency futures contract is an agreement between two parties to deliver a set amount of currency at a set date, called the expiry, in the future. Futures contracts are traded on an exchange for set values of currency and with set expiry dates. Unlike a forward, the terms of a futures contract are non-negotiable. A profit is made on the difference between the prices the contract was bought and sold at. Most speculators don't hold futures contracts until expiration, as that would require they deliver/settle the currency the contract represents. Instead, speculators buy and sell the contracts prior to expiration, realizing their profits or losses on their transactions.