A market is a mechanism which allows people to trade, normally governed by the theory of supply and demand. Both general and specialised markets, where only one commodity is traded, exist. Markets work by placing many interested sellers in one place, thus making them easier to find for prospective buyers. An economy which relies primarily on interactions between buyers and sellers to allocate resources is known as a market economy in contrast either to a command economy or to a non-market economy that is based, e.g., on gifts.

Marketplaces and street markets

The traditional market is a city square where traders set up stalls and buyers browse the merchandise. This kind of market is very old, and countless such markets are still in operation around the whole world.

• In the USA such markets fell out of favor, but renewed interest in local food has cause the reinvention of this type of market, called farmers' markets, in many towns and cities.
• In continental Europe, especially in France, street markets, as well as "marketplaces" (covered places where merchants have stalls, but not entire stores) are commonplace. Both resellers and producers sell their wares to the public.

An example of a large market is Chatuchak weekend market in Bangkok.

The Roman term for market, still in use in a related sense, is forum. The modern shopping mall can be seen as an extension of this concept.

Economic markets

In modern times, mainly after the invention of the electronic computer, markets are not always located in a physical space. Such virtual markets consist of communication paths where information exchange is easy and deals may be struck. A notable example of this is the international currency market.