Trade involves the transfer of goods or services from one person or entity to another, often in exchange for money. A system or network that allows trade is called a market.
When a general usage has been judicially ascertained and established, it becomes a part of the law merchant, which Courts of justice are bound to know and recognise.
Lord Campbell, Brandao v. Barnett (1846), 12 CI. & F. 805.
