Multi-party system

In political science, a multi-party system is a political system where more than two meaningfully-distinct political parties regularly run for office and win elections. Multi-party systems tend to be more common in countries using proportional representation compared to those using winner-take-all elections, a result known as Duverger's law.

In these countries, usually no single party has a parliamentary majority by itself (hung parliaments). Instead, multiple political parties must negotiate to form a coalition with a majority of the vote, in order to make substantial changes.

Comparisons with other party systems
Unlike a one-party system (or a dominant-party system), a multi-party system encourages the general constituency to form multiple distinct, officially recognized groups, generally called political parties. Each party competes for votes from the enfranchised constituents (those allowed to vote). A multi-party system prevents the leadership of a single party from controlling a single legislative chamber without challenge.

A system where only two parties have a realistic possibility of winning an election is called a two-party system. A system where only three parties have a realistic possibility of winning an election or forming a coalition is sometimes called a "third-party system".

A two-party system requires voters to align themselves in large blocks, sometimes so large that they cannot agree on any overarching principles. Some theories argue that this allows centrists to gain control, though this is disputed. On the other hand, if there are multiple major parties, each with less than a majority of the vote, the parties are strongly motivated to work together to form working governments. This also promotes centrism, as well as promoting coalition-building skills while discouraging polarization.

By country
Argentina, Armenia, Belgium, Brazil, Canada, Denmark, Finland, France, Germany, Iceland, India, Indonesia, Ireland, the Netherlands, New Zealand, Norway, the Philippines, Poland, Sweden, Tunisia, Turkey and Ukraine are examples of countries with multi-party systems.