Futures are a type of contract where a buyer and seller agree on a price on a particular item to be delivered on a certain date in the future, hence the name. (courant.com)
The contract is an agreement, or promise, for the buyer to purchase oil at a certain price in the future (the spot price) at a certain date in the future (the contract's maturity) from the seller. (wisestockbuyer.com)
A futures contract on a commodity is an agreement to deliver a certain commodity at a certain date in the future for a price paid today, such as paying $ 100 today for a barrel of oil to be delivered in three months. (tradinginsights.schwab.acsitefactory.com)