Currency Futures

You want to own a bunch of British pounds...three years from now. You're nervous about what Brexit will have done to the relative value of the pound compared with the dollar. You want to lock in the relative pricing, because you sell a low margin product, and if the currency goes just 5% against you, the big sale you made to the Brits will go from being profitable to...not.

So you buy a currency future, paying, say, 2% of the value for that currency to be delivered three years from now, in return for rates being locked. You can book your profits and be done with it, and move on to fight another day.