Futures are contracts to buy or sell a specific underlying asset at a future date. The underlying asset can be a commodity, a security, or other financial instrument. Futures trading requires the buyer to purchase or the seller to sell the underlying asset at the set price, whatever the market price, at the expiration date.
Stocks are ownership certificates of a specific company. When you own a stock, its corresponding value represents your share or partial ownership of the company.
Futures trading commonly refers to futures whose underlying assets are securities in the stock market. These contracts are based on the future value of an individual company's shares or a stock market index like the S&P 500, Dow Jones Industrial Average, or Nasdaq.
Futures trading on exchanges like the Chicago Mercantile Exchange can include underlying "assets" like physical commodities, bonds, or weather events.