The main purpose of political parties is to join people who hold similar points of view about the government together. These groups work to participate in and influence the government by having its members elected to a government position. Even though many people choose to be associated with a certain party, they don't all share exactly the same beliefs. However, the core beliefs about how government should be run are shared.
The United States is a two-party system. Although there are minor parties, none have been able to gain the support needed to win a national election. In America, we have a two-party system where the Republicans and Democrats dominate the political scene. However, there is a growing trend in the United States for voters to be registered as independent. This group votes for different parties in each election. An independent may vote for a Republican for president and a Democrat for senator. The Republicans and Democrats work hard to understand this group of voters.