The document discusses the American political party system. It begins by defining political parties and their role in organizing candidates and government. It then describes the historical development of parties in the US from factions in the 18th century to political machines to modern reform periods. The US has a federal constitutional democratic republic system with separation of powers between the executive, legislative and judicial branches. Politics are shaped by the two dominant parties, Democrats and Republicans, as well as citizen interests, lobbyists and media.