There are three major political parties in the United States. These three all have a substantial voter base. It is their general intention to dominate the way our Republic is governed.
Political parties are groups of like-minded people that organize competitions for political offices. In the broadest definition, political parties are the entire apparatus that supports the election of a group of candidates, including voters and volunteers who identify with a particular political party, the official party organizations that support the election of that party's candidates, and legislators in the government who are affiliated with the party.
Political parties are distinguished from other political groups and clubs, such as political factions or interest groups, mostly by the fact that parties are focused on electing candidates whereas interest groups are focused on advancing a policy agenda. This is related to other features that sometimes distinguish parties from other political organizations, including a larger membership, greater stability over time, and deeper connection to the electorate.
In some definitions of political parties, a party is an organization that advances a specific set of ideological or policy goals, or that organizes people whose ideas about politics are similar. However, many political parties are not primarily motivated by ideology or policy; for example, political parties can be mainly clientelistic or patronage based organizations, or tools for advancing the career of a specific political entrepreneur.