A forward contract is an agreement between two parties to buy or sell an asset (which can be of any kind) at a pre-agreed future point in time. Therefore, the trade date and delivery date are separated. It is used to control and hedge risk, for example currency exposure risk or commodity prices (e.g., forward contracts on oil).

One party agrees (obligated) to sell, the other to buy, for a forward price agreed in advance. In a forward transaction, no actual cash changes hands. If the transaction is collateralized, exchange of margin will take place according to a pre-agreed rule or schedule. Otherwise no asset of any kind actually changes hands, until the maturity of the contract.
A standardized forward contract that is traded on an exchange is called a futures contract.