Final answer:
The Defense of Marriage Act (DOMA) is a federal law that defined marriage as a union between a man and a woman, and allowed one state to not recognize a same-sex marriage or union from another state.
Step-by-step explanation:
The Defense of Marriage Act (DOMA) is a federal law passed in 1996 that defined marriage as a union between a man and a woman. It allowed one state to not recognize a same-sex marriage or union from another state. The law does not prohibit states from performing or recognizing same-sex marriages, but it does not compel a state to recognize the legality of same-sex marriages performed in other states.