A political party is made up of individuals who organize to win elections, operate government, and influence public policy. The Democratic and Republican parties are currently the primary parties in Congress.
A political party is an organization that coordinates candidates to compete in a particular country's elections. It is common for the members of a party to hold similar ideas about politics, and parties may promote specific ideological or policy goals.
Political parties have become a major part of the politics of almost every country, as modern party organizations developed and spread around the world over the last few centuries. It is extremely rare for a country to have no political parties. Some countries have only one political party while others have several. Parties are important in the politics of autocracies as well as democracies, though usually democracies have more political parties than autocracies. Autocracies often have a single party that governs the country, and some political scientists consider competition between two or more parties to be an essential part of democracy.
Parties can develop from existing divisions in society, like the divisions between lower and upper classes, and they streamline the process of making political decisions by encouraging their members to cooperate. Political parties usually include a party leader, who has primary responsibility for the activities of the party; party executives, who may select the leader and who perform administrative and organizational tasks; and party members, who may volunteer to help the party, donate money to it, and vote for its candidates. There are many different ways in which political parties can be structured and interact with the electorate. The contributions that citizens give to political parties are often regulated by law, and parties will sometimes govern in a way that favours the people who donate time and money to them.
Many political parties are motivated by ideological goals. It is common for democratic elections to feature competitions between liberal, conservative, and socialist parties; other common ideologies of very large political parties include communism, populism, nationalism, and Islamism. Political parties in different countries will often adopt similar colours and symbols to identify themselves with a particular ideology. However, many political parties have no ideological affiliation, and may instead be primarily engaged in patronage, clientelism, or the advancement of a specific political entrepreneur.
According to Anson D. Morse, a political party is a durable organization united by common principles which "has for its immediate end the advancement of the interests and the realization of the ideals... of the particular group or groups which it represents."
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 a deeper connection to the electorate.
The idea of people forming large groups or factions to advocate for their shared interests is ancient. Plato mentions the political factions of Classical Athens in the Republic, and Aristotle discusses the tendency of different types of government to produce factions in the Politics. Certain ancient disputes were also factional, like the Nika riots between two chariot racing factions at the Hippodrome of Constantinople. A few instances of recorded political groups or factions in history included the late Roman Republic's Populares and Optimates factions as well as the Dutch Republic's Orangists and the Staatsgezinde. However, modern political parties are considered to have emerged around the end of the 18th century; they are usually considered to have first appeared in Europe and the United States of America, with the United Kingdom's Conservative Party and the Democratic Party of the United States both frequently called the world's "oldest continuous political party".
At the end of the century, the United States also developed a party system, called the First Party System. Although the framers of the 1787 United States Constitution did not all anticipate that American political disputes would be primarily organized around political parties, political controversies in the early 1790s over the extent of federal government powers saw the emergence of two proto-political parties: the Federalist Party and the Democratic-Republican Party.
The strength of political parties in the United States waned during the Era of Good Feelings, but shifted and strengthened again by the second half of the 19th century. This was not the only country in which the strength of political parties had substantially increased by the end of the century; for example, around this time the Irish political leader Charles Stewart Parnell implemented several methods and structures like party discipline that would come to be associated with strong grassroots political parties.
As broader suffrage rights and eventually universal suffrage slowly spread throughout democracies, political parties expanded dramatically, and only then did a vision develop of political parties as intermediaries between the full public and the government.
One of the core explanations for the existence of political parties is that they arise from pre-existing divisions among people: society is divided in a certain way, and a party is formed to organize that division into the electoral competition. By the 1950s, economists and political scientists had shown that party organizations could take advantage of the distribution of voters' preferences over political issues, adjusting themselves in response to what voters believe in order to become more competitive. Beginning in the 1960s, academics began identifying the social cleavages in different countries that might have given rise to specific parties, such as religious cleavages in specific countries that may have produced religious parties there.
An alternative explanation for why parties are ubiquitous across the world is that the formation of parties provides compatible incentives for candidates and legislators. For example, the existence of political parties might coordinate candidates across geographic districts, so that a candidate in one electoral district has an incentive to assist a similar candidate in a different district. Thus, political parties can be mechanisms for preventing candidates with similar goals from acting to each other's detriment when campaigning or governing. This might help explain the ubiquity of parties: if a group of candidates form a party and are harming each other less, they may perform better over the long run than unaffiliated politicians, so politicians with party affiliations will out-compete politicians without parties.
Parties can also align their member's incentives when those members are in a legislature. The existence of a party apparatus can help coalitions of electors to agree on ideal policy choices, whereas a legislature of unaffiliated members might never be able to agree on a single best policy choice without some institution constraining their options.
Another prominent explanation for why political parties exist is psychological: parties may be necessary for many individuals to participate in politics because they provide a massively simplifying heuristic, which allows people to make informed choices with much less mental effort than if voters had to consciously evaluate the merits of every candidate individually. Without political parties, electors would have to individually evaluate every candidate in every election. But political parties enable electors to make judgments about just a few groups, and then apply their judgment of the party to all the candidates affiliated with that group. Because it is much easier to become informed about a few parties' platforms than about many candidates' personal positions, parties reduce the cognitive burden for people to cast informed votes. However, evidence suggests that over the last several decades, the strength of party identification has been weakening, so this may be a less important function for parties to provide than it was in the past.
Parties are typically led by a party leader, who serves as the main representative of the party and often has primary responsibility for overseeing the party's policies and strategies. The leader of the party that controls the government usually becomes the head of government, such as the president or prime minister, and the leaders of other parties explicitly compete to become the head of government. In both presidential democracies and parliamentary democracies, the members of a party frequently have substantial input into the selection of party leaders, for example by voting on party leadership at a party conference. Because the leader of a major party is a powerful and visible person, many party leaders are well-known career politicians. Party leaders can be sufficiently prominent that they affect voters' perceptions of the entire party, and some voters decide how to vote in elections partly based on how much they like the leaders of the different parties.
The number of people involved in choosing party leaders varies widely across parties and across countries. On one extreme, party leaders might be selected from the entire electorate; on the opposite extreme, they might be selected by just one individual. Selection by a smaller group can be a feature of party leadership transitions in more autocratic countries, where the existence of political parties may be severely constrained to only one legal political party, or only one