A commodity is a basic good used in commerce that is interchangeable with other goods of the same type. Commodities are most often used as inputs in the production of other goods or services. A commodity thus usually refers to a raw material used to manufacture finished goods.
Forex (FX) refers to the global electronic marketplace for trading international currencies and currency derivatives. It has no central physical location, yet the forex market is the largest, most liquid market in the world by trading volume, with trillions of dollars changing hands every day. Most of the trading is done through banks, brokers, and financial institutions.
Indexes are a group or basket of securities, derivatives, or other financial instruments that represents and measures the performance of a specific market, asset class, market sector, or investment strategy.