A political party is a group of people who come together to contest elections and hold power in the government. The party agrees on some proposed policies and programmes, with a view to promoting the collective good or furthering their supporters' interests.
While there is some international commonality in the way political parties are recognized, and in how they operate, there are often many differences, and some are significant. Many political parties have an ideological core, but some do not, and many represent very different ideologies than they did when first founded. In democracies, political parties are elected by the to run a government. Many countries have numerous powerful political parties, such as Germany and India and some nations have one-party systems, such as China and Cuba. The United States is in practice a two-party system, with many smaller parties participating. Its two most powerful parties are the Democratic Party and the Republican Party.
The first political factions, cohering around a basic, if fluid, set of principles emerged from the Exclusion Crisis and Glorious Revolution in late-17th-century England. The Whigs supported Protestant constitutional monarchy against absolute rule and the Tories, originating in the Royalist (or "Cavalier") faction of the English Civil War, were conservative royalist supporters of a strong monarchy as a counterbalance to the republican tendencies of Whigs, who were the dominant political faction for most of the first half of the 18th century; they supported the Hanoverian succession of 1715 against the Jacobite supporters of the deposed Roman Catholic Stuart dynasty and were able to purge Tory politicians from important government positions after the failed Jacobite rising of 1715. The leader of the Whigs was Robert Walpole, who maintained control of the government in the period 1721–1742; his protégé was Henry Pelham (1743–1754).