Mishnah Kiddushin 1:1 specifies that a woman is acquired (i.e., to be a wife) in three ways: through money, a contract, and sexual intercourse. Ordinarily, all three of these conditions are satisfied, although only one is necessary to effect a binding marriage.
Acquisition by money is normally satisfied by the wedding ring. It is important to note that although money is one way of "acquiring" a wife, the woman is not being bought and sold like a piece of property or a slave. This is obvious from the fact that the amount of money involved is nominal (according to the Mishnah, a perutah, a copper coin of the lowest denomination, was sufficient). In addition, if the woman were being purchased like a piece of property, it would be possible for the husband to resell her, and clearly it is not. Rather, the wife's acceptance of the money is a symbolic way of demonstrating her acceptance of the husband, just like acceptance of the contract or the sexual intercourse.
To satisfy the requirements of acquisition by money, the ring must belong to the groom. It cannot be borrowed, although it can be a gift from a relative. It must be given to the wife irrevocably. In addition, the ring's value must be known to the wife, so that there can be no claim that the husband deceived her into marrying by misleading her as to its value.
In all cases, the Talmud specifies that a woman can be acquired only with her consent, and not without it. Kiddushin 2a-b.
As part of the wedding ceremony, the husband gives the wife a ketubah. The word "Ketubah" comes from the root Kaf-Tav-Beit, meaning "writing." The ketubah is also called the marriage contract. The ketubah spells out the husband's obligations to the wife during marriage, conditions of inheritance upon…