Most companies are classified according to the industry they will operate in. Some of these will be large companies that focus on a specific type of industry, including Apple or Walmart, whilst other folks specialize in a particular type of services or products. Examples of market sectors in which businesses may work include promoting, mattress creation, real estate, and oil. ExxonMobil, for instance, functions business by giving oil to customers. Various other industries include restaurants, shops, and other small enterprises.