The act of marriage usually creates normative or legal obligations between the individuals involved, and any offspring they may produce or adopt.
In terms of legal recognition, most sovereign states and other jurisdictions limit marriage to opposite-sex couples and a diminishing number of these permit polygyny, child marriages, and forced marriages.
Over the twentieth century, a growing number of countries and other jurisdictions have lifted bans on and have established legal recognition for interracial marriage, interfaith marriage, and most recently, gender-neutral marriage.
Conversely, civil marriage does not exist in some countries governed by a religious legal system, such as Saudi Arabia, where marriages contracted abroad might not be recognized if they were contracted contrary to Saudi interpretations of Islamic religious law.
In countries governed by a mixed secular-religious legal system, such as in Lebanon and Israel, locally performed civil marriage also does not exist within the country, preventing interfaith and various other marriages contradicting religious laws from being entered into in the country, however, civil marriages performed abroad are recognized by the state even if they conflict with religious laws (in the case of recognition of marriage in Israel, this includes recognition of not only interfaith civil marriages performed abroad, but also overseas same-sex civil marriages).
Conversely, such practices may be outlawed and penalized in parts of the world out of concerns of the infringement of women's rights, or the infringement of children's rights (both female and male children), and because of international law.
In developed parts of the world, there has been a general trend towards ensuring equal rights within marriage for women and legally recognizing the marriages of interfaith, interracial, and same-sex couples.
In The History of Human Marriage (1922), Edvard Westermarck defined marriage as "a more or less durable connection between male and female lasting beyond the mere act of propagation till after the birth of the offspring." In The Future of Marriage in Western Civilization (1936), he rejected his earlier definition, instead provisionally defining marriage as "a relation of one or more men to one or more women that is recognized by custom or law".
The anthropological handbook Notes and Queries (1951) defined marriage as "a union between a man and a woman such that children born to the woman are the recognized legitimate offspring of both partners." In recognition of a practice by the Nuer people of Sudan allowing women to act as a husband in certain circumstances (the ghost marriage), Kathleen Gough suggested modifying this to "a woman and one or more other persons." In an analysis of marriage among the Nayar, a polyandrous society in India, Gough found that the group lacked a husband role in the conventional sense; that unitary role in the west was divided between a non-resident "social father" of the woman's children, and her lovers who were the actual procreators.In some areas, child marriages and polygamy may occur in spite of national laws against the practice.Since the late twentieth century, major social changes in Western countries have led to changes in the demographics of marriage, with the age of first marriage increasing, fewer people marrying, and more couples choosing to cohabit rather than marry.In Europe, the United States, and other places in the developed world, beginning in the late 19th century and lasting through the 21st century, marriage has undergone gradual legal changes, aimed at improving the rights of the wife.These changes included giving wives legal identities of their own, abolishing the right of husbands to physically discipline their wives, giving wives property rights, liberalizing divorce laws, providing wives with reproductive rights of their own, and requiring a wife's consent when sexual relations occur.In some cultures, marriage is recommended or considered to be compulsory before pursuing any sexual activity.