A market is a group of buyers and sellers of a particular good or service. The buyers as a group determine the demand for the product, and the sellers as a group determine the supply of the product. Markets take many forms. Some markets are highly organized, such as the markets for many agricultural commodities. In these markets, buyers and sellers meet at a specific time and place, where an auctioneer helps set prices and arrange sales. More often, markets are less organized. For example, consider the market for ice cream in a particular town. […] Nonetheless, these consumers and producers of ice cream are closely connected.
N. Gregory Mankiw, Principles of Economics (6th ed., 2012), Ch. 4. The Market Forces of Supply and Demand