A future contract bides the buyer to purchase an asset from the seller at a set price at a future point in time (mentioned in the agreement) on publicly-traded exchange. The contract obliges the seller to sell the asset. 

In future contract, asset implies to a commodity, stock, bond, or currency. Some future contract allows the buyer to pay in cash instead of delivery.

What future contract does?

Through mutually agreeing and signing future contracts future traders do not primarily seek profit by trading commodities future. The main purpose is to seek to achieve a gentle revenue of the cost of their business operations.