Trade is the willing exchange of goods, services, or both. Trade is also called commerce. A mechanism that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and services. Modern traders instead generally negotiate through a medium of exchange, such as money.

As a result, buying can be separated from selling, or earning. The invention of money (and later credit, paper money and non-physical money) greatly simplified and promoted trade. Trade between two traders is called bilateral trade, while trade between more than two traders is called multilateral trade.

Trade exists for many reasons. Due to specialization and division of labor, most people concentrate on a small aspect of production, trading for other products.

Trade exists between regions because different regions have a comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production. As such, trade at market prices between locations benefits both locations.

Trading can also refer to the action performed by traders and other market agents in the financial markets.

Trade originated with the start of communication in prehistoric times. Trading was the main facility of prehistoric people, who bartered goods and services from each other before the innovation of the modern day currency. Peter Watson dates the history of long-distance commerce from circa 150,000 years ago.

Trade is believed to have taken place throughout much of recorded human history. There is evidence of the exchange of obsidian and flint during the stone age. Materials used for creating jewelry were traded with Egypt since 3000 BC. Long-range trade routes first appeared in the 3rd millennium BC, when Sumerians in Mesopotamia traded with the Harappan civilization of the Indus Valley.

The Phoenicians were noted sea traders, traveling across the Mediterranean Sea, and as far north as Britain for sources of tin to manufacture bronze.

For this purpose they established trade colonies the Greeks called emporia. From the beginning of Greek civilization until the fall of the Roman empire in the 5th century, a financially lucrative trade brought valuable spice to Europe from the far east, including China.

Roman commerce allowed its empire to flourish and endure. The Roman empire produced a stable and secure transportation network that enabled the shipment of trade goods without fear of significant piracy.

The fall of the Roman empire, and the succeeding Dark Ages brought instability to Western Europe and a near collapse of the trade network. Nevertheless some trade did occur.

For instance, Radhanites were a medieval guild or group (the precise meaning of the word is lost to history) of Jewish merchants who traded between the Christians in Europe and the Muslims of the Near East.

The Sogdians dominated the East-West trade route known as the Silk Road after the 4th century AD up to the 8th century AD, with Suyab and Talas ranking among their main centeres in the north. They were the main caravan merchants of Central Asia.