A political party is an organization aiming to acquire and exercise political power, typically with some stated purpose, such as an ideology or to support the special interests of certain groups, such as ethnic and/or religious groups.
While the term originated in the context of organizations competing in elections in democracies, the term is now used more widely, such as regarding "one-party system" countries only allowing one party.
Other kinds of organizations may also have political aims, including in countries allowing no formal parties, but where there may be lobby organizations and informal factions, aiming to achieve various political goals.
In "two-party systems", two major political parties dominate politics, often due to the electoral system favoring the two largest parties, sometimes to the extent that other parties ("third parties") rarely win any seats in the legislature.
Two-party systems are often claimed, as a main advantage, to be more stable than multi-party systems, although this may depend on factors such there being low polarization and high social trust in the country, with a two-party system possibly risking increasing the polarization in a polarized society even further. A 2016 study on insurgencies and civil wars in ethnically heterogeneous Latin America (with high ethnic heterogeneity tending to increase polarization and decrease social trust) stated that "two-party systems may polarize and lead to intense insurgency because they simplify the process of blame attribution, encourage the incumbent party to exclude its opponent from power positions, and motivate leaders to emphasize extreme ideological positions."
- How Do Party Systems Shape Insurgency Levels? A Comparison of Four Nineteenth-Century Latin American Republics https://www.cambridge.org/core/journals/social-science-history/article/how-do-party-systems-shape-insurgency-levels-a-comparison-of-four-nineteenthcentury-latin-american-republics/1D89E39A48F7FCC7AC426C0613B68898