Compared with buying and selling marriage, asking for property through marriage involves asking for property, but they are different in essence. The former is at most an immoral act, while the latter is a fundamental illegal act. For a marriage in which property is demanded through marriage, both parties are completely willing to establish the marriage, so the marriage relationship is completely legal and effective; Buying and selling marriage is against the will of the parties to the marriage and belongs to arranged marriage, which is strictly prohibited by law. If the property demanded by the marriage relationship is not married for a long time or causes the other party's living difficulties due to the demand for property, all or part of the property may be returned at the discretion of the two parties at the time of divorce. Marriage is legally called marriage establishment. It refers to the civil legal act that both men and women or partners establish the husband and wife relationship in accordance with the conditions and procedures prescribed by law, and assume the rights, obligations and other responsibilities arising therefrom. Nowadays, many countries in the world have passed legislation, making it clear that the object of marriage can be the opposite sex or the same sex, including the United States, Germany, the Netherlands and so on. In China, marriage legally refers only to the union between men and women of the opposite sex. However, deputies to the National People's Congress have suggested to the legislature that same-sex couples should be allowed to marry. Although the law has not yet recognized, in reality, many homosexuals have formed de facto marriages through rituals or cohabitation. "The age of marriage shall not be earlier than 22 years for men and 20 years for women. Late marriage and late childbearing shall be encouraged." Legal interpretation of the concept of marriage: The Marriage Law of the People's Republic of China stipulates the legal conditions for legal marriage of both sexes, the rights and obligations of both men and women after marriage, and other responsibilities and obligations arising therefrom. The establishment of marriage has three basic legal characteristics.
 1、 The subject of marriage is male and female. Marriage is not constituted by the combination of physiological differences between men and women. People of the same sex cannot marry.
 2、 Marriage is a legal act. Both parties applying for marriage must abide by the provisions of the law and perform the marriage registration procedures prescribed by the law. Otherwise, the marriage relationship will not have legal consequences. That is, invalid marriage not protected by law must meet the substantive and formal requirements specified in the Marriage Law of the People's Republic of China, otherwise it will not have the effect of legal marriage.
 3、 The legal consequence of marriage is to establish the husband and wife relationship between the two parties. And bear the responsibilities, rights and obligations arising therefrom. Without legal procedures, no unit, individual or both husband and wife have the right to terminate the established marital relationship.
 4、 The prerequisites for marriage are: first, both men and women are completely voluntary; second, they must reach the legal age; third, they must conform to the monogamy.
 5、 Prohibition conditions for marriage: First, marriage between direct relatives by blood and collateral relatives by blood within three generations is prohibited. Second, it is prohibited to marry people who suffer from diseases that medical science believes should not be married.