The United States is a representative democracy. Citizens elect representatives to national, state, and local government; those representatives create the laws that govern U.S. society.
Although individual citizens are the only ones who can cast votes, special interest groups and lobbyists influence elections and law-making with money and other resources. At times, this influence has grown so noticeable that some have called into question whether the U.S. is truly a democracy of the people or something more like an oligarchy of special interest groups. The media also play an important role in politics by influencing public sentiment and acting as an information filter.
U.S. federal government is composed of three distinct branches— legislative, executive, and judicial — whose powers are vested by the U.S. Constitution in the Congress, the President, and the federal courts, including the Supreme Court, respectively.
Although nothing in U.S. law requires it, in practice, the political system is dominated by political parties. Elections are decided between the two major parties, Democrats and Republicans.
Understanding how our elected politicians are performing their responsibilities in passing good public policies it is important to look at their records to verify if their actions are in line with your expectations.