Common law marriage—also known as marriage without formalities or informal marriage—is marriage without a wedding or marriage ceremony and without a marriage license. Some states recognize common law marriage under certain circumstances—such as when the parties agree to be married, live together (cohabit) after agreeing to be married, and represent to others that they are married (holding themselves out as a married couple).

Other states previously recognized common law marriages, but no longer recognize such marriages after a certain date on which the law was changed—usually by statute. In other states, common law marriage has not been recognized by the legislature in a statute, but the courts have recognized common law marriage in court opinions or case law.

California does not recognize common law marriages created within the state. This means that couples who cohabit and hold themselves out as married without formalizing their relationship through a marriage license and ceremony are not considered legally married in California. However, California does recognize common law marriages that were legally established in other states where common law marriage is recognized. This means that if a couple legally enters into a common law marriage in a state that recognizes such unions, and then moves to California, their marriage will be recognized by California law. It's important for individuals in such relationships to understand that without a recognized marriage, they may not have the legal rights and benefits that are conferred upon married couples, such as property rights, inheritance rights, or spousal support in the event of a separation.