Even if the United States had an absolute advantage in both coffee and air traffic control systems, it should still specialize and engage in trade. Why? The reason is the principle of comparative advantage, which says that each country should specialize in the products that it can produce most readily and cheaply and trade those products for goods that foreign countries can produce most readily and cheaply. This specialization ensures greater product availability and lower prices.

Each year the United States exports more food, animal feed, and beverages than the year before. A third of U.S. farm acreage is devoted to crops for export. The United States is also a major exporter of engineering products and other high-tech goods, such as computers and telecommunications equipment. For more than 60,000 U.S. companies (the majority of them small), international trade offers exciting and profitable opportunities. Among the largest U.S. exporters are Apple, General Motors Corp., Ford Motor Co., Procter & Gamble, and Cisco Systems.

Social factors—our attitudes, values, ethics, and lifestyles—influence what, how, where, and when people purchase products or services. They are difficult to predict, define, and measure because they can be very subjective. They also change as people move through different life stages. People of all ages have a broader range of interests, defying traditional consumer profiles.