American Politics studies political institutions, processes, and behaviors at the national and state level. The study of political institutions encompasses both the formal ones (Congress, the Presidency, and the Judiciary) and such important informal institutions as political parties, interest groups, and the media. Examples of political processes are elections and law making. The study of political behavior focuses on political participation, public opinion, and the behavior of political elites (e.g. roll-call behavior). American politics also studies the relationship between national and state governments (federalism) as established in the Constitution, as it has evolved historically, and as it currently stands.