Trade is the voluntary exchange of goods and services. Trade is also known as commerce. Trade proceeds within a market. The most primitive form of trade is to exchange goods for goods, that is to exchange goods or services directly. Modern trade in general uses a medium to bargain, for example the use of money. The appearance of money (and the latter L/C, cheque, virtual money) hugely simplifies and promotes trade. The trade between two traders is known as bi-lateral trade. The trade involving more than two traders is known as multi-lateral trade.

Màoyì shì zìyuàn de huòpǐn huò fúwù jiāohuàn. Màoyì yě bèi chēngwéi shāngyè. Màoyì shì zài yīgè shìchǎng lǐmiàn jìnxíng de. Zuì yuánshǐ de màoyì xíngshì shì yǐwùyìwù, yějiùshì zhíjiē jiāohuàn huòpǐn huò fúwù. Xiàndài de màoyì zé pǔbiàn yǐ yīzhǒng méijiè zuò tǎojiàhuánjià, rú jīnqián. Jīnqián de chūxiàn (yǐjí hòulái de xìnyòngzhèng, chāopiào yǐjí fēi-shítǐ jīnqián) dàdà jiǎnhuà hé cùjìnle màoyì. Liǎnggè màoyìzhě zhījiān de màoyì chēngwéi shuāngbiān màoyì, duōyú liǎnggè màoyìzhě de zé chēngwéi duōbiān màoyì.