Most companies are classified based on the industry they operate in. Some of these are large firms that give attention to a specific type of industry, just like Apple or Walmart, whilst other folks specialize in a particular type of product or service. Examples of companies in which businesses may handle include advertising, mattress creation, real estate, and oil. ExxonMobil, for instance, runs business by providing oil to customers. Other industries include restaurants, retailers, and other small businesses.