Consideration 对价Something bargained for and received by a promisor from a promisee. Common types of consideration include real or personal property, a return promise, some act, or a forbearance. Consideration or a valid substitute is required to have a contract. Consideration is one of the three basic elements of contract formation in common law, the other two being offer and acceptance. it is not present in other legal systems.立诺人从承诺人那里讨价还价并得到的东西。
常见的对价类型包括不动产或动产、回报承诺、某种作为或不作为。
合同要求有对价或者有效的替代物。
在英美法中，对价是合同形成的三个基本要素之一，其他两个要素是要约和承诺。
这在其他法律体系中是不存在的。
1. Definition of Consideration 对价的定义There are various definitions to consideration,likeConsideration is some benefit received by a party who gives a promise or performs an act, or some detriment suffered by a party who receives a promise.“A valuable consideration, in the sense of the law, may consist either in some right, interest, profit of benefit accruing to one party or some forbearance,detriment, loss or responsibility given, suffered or undertaken by the other.”对价有多种定义，比如：对价是指承诺人或者行为人获得的利益，或者承诺人受到的损害。
从法律意义上讲，有价值的对价可以包括一方获得的某种权利、利益、利益收益，也可以包括另一方给予、遭受或承担的某种宽容、损害、损失或责任。
Consideration means something which is of some value in the eye of the law, moving from the plaintiff; it may be some detriment to the plaintiff or some benefit to the defendant, but at all events it must be moving from the plaintiff.Accordingly, consideration is either some detriment to the promisee or some benefit to the promisor. A valid consideration must be executory or executed; it cannot be past.对价是指在法律看来具有一定价值的、从原告转移而来的东西;它可能对原告不利，也可能对被告有利，但无论如何，它必须是从原告那里转移来的。
因此，对价要么是对被承诺人的一种损害，要么是对承诺人的一种利益。
有效的对价必须是可执行的或正在执行的;它不可能是过去的。
Executory -- a promise to do something in the future (e. g. A promises to deliver goods to B and B promises to pay for the goods);Executed -- an act constituting the consideration is whollyperformed (e. g. the payment of money for goods; the return of a lost dog, for which a reward has been offered).可执行的——承诺在未来做某事(例如，A承诺向B交付货物，B 承诺支付货款);已执行的——构成对价的行为已全部执行(例如，支付货款;归还一只丢失的狗，对此已给予酬谢）。
Consideration is something bargained for and given in exchange for a promise. That ‘something" may be an act, a forbearance, or a return promise. It may either be a benefit to the promisor or a detriment to the promisee. To be constitute consideration, there must be a detriment to the promisee.Consideration is some benefit received by a party who gives a promise or performs an act, or some detriment suffered by a party who receives a promise. A valid consideration must be executory or executed; it cannot be past.对价是一种以承诺为交换条件而讨价还价的东西。
那个“东西”可能是一种行为、一种忍耐，或者一种回报承诺。
它要么对承诺人有利，要么对承诺人不利。
要构成对价，必须损害到受约人的利益。
对价是指承诺人或者行为人获得的利益，或者受诺人受到的损害。
有效的对价必须是可执行的或者已执行的;它不能是过去的。
2.Charateristics of Consideration 对价的特征(1)It must be real and of some value. It must not be vague,indefinite or abstract.(2) It need not be adequate. This principle is sometimes explained as "consideration need not be equal to the promise" or " consideration may not be adequate but must be sufficient."(3) It must be legal. An illegal consideration makes the whole contract invalid.(4) It must move from the promisee, i. e. only the person who has paid the price for a promise can sue on it.(5) It must be possible to perform. A promise to do the impossible would not be accepted as consideration.(6)It must not be past. If the act put forward as consideration was performed before any promise of reward was made it is not valid consideration. The general rule is that " past consideration is no consideration."(7) Performance of an existing contractual duty, or a public duty imposed on the promisee by law, there will not amount to consideration unless the promisee goes beyond what he is required to do.(1)它必须是真实的并且有一定的价值。
它不能含糊、不明确或抽象。
(2)它不一定是适当的。
这一原则有时被解释为“对价不一定等于承诺”或“对价不一定适当，但必须充分”。
(3)它必须是合法的。
非法的对价使整个合同无效。
(4)它必须从承诺人处转移来，即只有为承诺付出代价的人才能对其提起诉讼。
(5)它必须是能够执行的。
承诺去做不可能的事不会被作为对价接受的。
(6)一定不能过去。
如果作出考虑的行为是在作出任何奖励承诺之前进行的，那么这是无效的考虑因素。
一般规则是“过去的考虑不予考虑”。
(7)履行现有的合同义务，或法律规定对受诺人施加的公共责任，除非受约人超出他的要求，否则不予考虑。
3. Exceptions of Consideration RequirementA contract without consideration can be invalid or unenforceable unless it is under seal. The doctrine is not suitable to the practice of today; therefore, there are two exceptions to this doctrine, they are:(1) Accord and SatisfactionThe general rule of the common law is that a creditor is not bound by an undertaking to accept part payment in full settlement of debt. An accrued debt can be discharged only by accord and satisfaction. The actual part payment is no satisfaction, that is to say, " payment of a lesser sum on the day in satisfaction of a greater sum cannot be any satisfaction for the whole."3.对价要求的例外情况未经对价的合同可能无效或无法执行，除非它是盖印合同。