Political parties are complex organizations that serve several functions in the US political system. They organize elections, help candidates get elected, and work to advance their policy platforms. Parties have different components, including the party in government made up of elected officials, the party in the electorate of citizens who identify with the party, and formal party organizations. While parties have dominated US politics for over 200 years, minor third parties face challenges to disrupting the two-party system due to electoral and legal barriers.