Most businesses are classified based on the industry they operate in. Some of these are large businesses that concentrate on a specific form of industry, such as Apple or perhaps Walmart, whilst require professional or technical disciplines others specialize in a certain type of product or service. Examples of market sectors in which businesses may perform include marketing and advertising, mattress creation, real estate, and oil. ExxonMobil, for instance, runs business by giving oil to customers. Additional industries consist of restaurants, stores, and other small enterprises.