Futures are derivatives, or contracts, where two parties have an agreement for the purchase of an asset at a specific price on a specific date.
This helps the one side have certainty in the price of an asset in the future, regardless of fluctuations, and it helps the other side make a bet and potentially profit from it (or to also have certainty if they had the opposite concern of the other person). Both sides could also be speculators, but with differing opinions.