The exchange of things of value, none of them being money. Barter is distinguished from a sale, where one of the things is money. As trading must have existed long before even the rudest kind of money was invented, Barter must have preceded sales properly so called. In the "Iliad" the Greeks before Troy buy wine of the ships coming from Lemnos, some of them with bronze or iron, some with skins, others with oxen or with slaves: this was many centuries after Abraham had bought a field with ready money. But little or nothing is found in the ancient laws of Greeks, Romans, or Hebrews to regulate Barter as distinguished from sale. It has been shown in the article Alienation that the form of Barter was often given to a purchase and sale; a handkerchief or some implement ("keli") being received as the equivalent for a house or field, or for a draft-animal. This was done, of course, as a mere formality, the real price being paid thereafter, or perhaps before, in money, or in a written or oral promise of money, this mode of passing the title being known as exchange ("ḥalippin").
From the treatment of this matter in Mishnah and Gemara it is pretty evident that a real Barter was seldom in contemplation when the parties went through its forms. Where the Babylonian Talmud speaks of overreaching (B. M. iv. 3, 4)—that is, buying goods at one-sixth below, or selling them at one-sixth above, the market price—it does not specially apply the rule to Barter, where the goods on both sides would have to be valued. Exchanges between goods of different kind are, however, alluded to in the treatment of the laws of usury (B. M. v. 1), as such an exchange may be resorted to where one of the commodities is about to rise in value, to cover up usury.
The Palestinian Talmud, however, where it discusses "onaäh" (overreaching, B. M. v. 10b), intimates that it may apply in cases of actual Barter. Maimonides ("Yad," Mekirah, xiii. 1) draws the conclusion that where an animal is exchanged for an animal, or an implement for an implement, mere inadequacy of values is no ground for complaint by either party, because each may have a predilection for the article he gets, but that it is otherwise in exchange of produce ("perot"), as here the value given on either side is strictly commercial. The commentators on Maimonides, ad loc., are strangely divided on this passage; and the subject is evidently one which came but seldom, if ever, into practical discussion before the judges.
In cases, however, in which a purchase or sale might be set aside for fraud, accident, or mistake ("miḳḳaḥ ṭa'ut"), a trade by Barter would fall under like rules; thus the case is put (Ḥoshen Mishpaṭ, 224, 1) where A trades his cow with B for an ass; the latter takes possession of the cow, but before A can take possession of the ass, the ass dies; B would have to bring forward proof that his ass was alive when the trade was clinched by the taking possession ("meshikah") of the cow (see Alienation and Fraud and Mistake).