commerce
The buying and selling of goods and services.
Commerce is the buying and selling of goods and services, especially on a large scale. When a farmer sells wheat to a baker, who bakes bread and sells it to customers, that's commerce. When a toy manufacturer in China ships products to stores across America, that's international commerce.
Commerce keeps economies running. It connects people who make things with people who need them. A smartphone involves commerce at every step: mining companies sell raw materials to manufacturers, manufacturers sell phones to retailers, and retailers sell them to customers. Each exchange is part of the vast network of commerce.
Before modern commerce, most families made or grew nearly everything they needed themselves. Today, commerce lets people specialize: some become expert farmers, others expert engineers, and through buying and selling, everyone gets what they need.
You'll also hear related terms: an online store might be called an e-commerce business (electronic commerce), and commerce between different countries is called international trade. The Department of Commerce is the part of the U.S. government that helps American businesses succeed and tracks economic activity. When someone has a commercial mindset, they're thinking about how to make business work profitably.