A Futures Contract is an agreement to buy or sell a commodity at a fixed time in the future executed on or with an Exchange

Detail

Note the similarity in description to a Forward Contract

We will focus mainly on the differences

Exchanges list standardized products that may be traded. A product describes a standardized commodity, delivery period and delivery location that may be traded

Exchanges list a buy and a sell price for every different product they list. These buy and sell prices are provided by Market Makers

Futures Contracts are always cleared

Futures Contracts may be physically or financially settled

A financially settled futures contract may be taken into the delivery period, and is settled by daily margining at the daily fixed in price

If you're wondering how that is different to an exchange-traded swap - then the difference is a swap is very like a financially settled futures contract, but the swap is generally not daily margined