Consideration is an important term in english and american contract law , and it is a body of rules enriched by the development of common law . there are many rules about consideration , among which the following may be most frequently mentioned : past consideration is no consideration ; consideration is provided by the promisee , though not necessarily to the promisor ; the adequacy and sufficiency of consideration 对价是英美合同法中的一个重要术语，有关对价的制度是随着普通法的历史发展而不断丰富起来的规则体系，有关对价的规则主要有：既往对价不是对价；对价一般由受约人提供，但不一定提供给立约人；对价的充足与充分。
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From the view of third party , it is named the contract for the benefit of third party . but the parties of the contract for the benefit of third party yet are promisor and promisee , the third party is not the contract party . so it is not necessary for third party to have capacity to contract , to make acceptance , even to know it , when the contract is made 第三人利益合同并非是合同的一个独特类型，它是合同内容中附有“利益第三人约款” ，从第三人的角度，将其称为第三人利益合同，但是第三人利益合同的缔结者仍然是约定人和受约人，因此第三人利益合同的成立，并不以第三人有行为能力为必要，也无需第三人承诺，甚至亦无需第三人知悉，只要第三人在合同履行时能确定即可。
