Derivatives derive their value from an underlying asset. They are financial contracts between parties, and changes in the underlying asset affect the derivative's price. There are two main types: forwards, privately negotiated contracts; and futures, exchange-traded contracts that are standardized. Participants use derivatives to hedge risk, speculate, or arbitrage between markets. Basic terms include long/short positions, expiry dates, and margins. Futures and forwards lock in today's price for an asset to be bought/sold in the future. Futures are margined daily based on the settlement price, while forwards involve payment at expiry.