A more thorough explanation:

Common law marriage is a type of marriage that does not require a formal ceremony or a marriage license. It is formed when two people live together and hold themselves out to others as a married couple. Although simply living together is not enough to establish a common law marriage, it is an important factor in determining whether a common law marriage exists.

For example, if a couple lives together for many years and presents themselves to others as a married couple, they may be considered to have a common law marriage. However, if they simply live together without holding themselves out as married, they would not have a common law marriage.

Most states have abolished common law marriage, but some still recognize it. In those states, a common law marriage that was formed before a certain date may still be recognized. Additionally, all states must recognize common law marriages that were formed in other states under the Full Faith and Credit Clause of the U.S. Constitution.