Political parties serve several functions including helping to unify the electorate, organize the government, and translate public preferences into policy. They also provide competition through elections and a loyal opposition. Parties nominate candidates through primary elections or party conventions and caucuses. The U.S. has a two-party system that tends toward stability through a winner-take-all approach, though minor parties still exist to represent single issues or ideological stances. Over time, the party system and voter preferences have undergone some realignment as new issues and coalitions emerge.