A party system is a concept in political science concerning the system of government in a state where political parties exist.

The party system of a state determines how many political parties in a state have a realistic chance of becoming the government, usually through winning elections. Party systems can either be created either usually created by a variety of factors, such as the type of electoral system used in a state. For example, the use of First Past the Post in elections to a state's primary legislative assembly (for example general elections) usually results in a two-party system.

There are four distinct types:

• single-party system - when only one party can be the government because all other parties are banned
• two-party system - when only two parties can realistically compete to become the government.
• dominant-party system - when only one party can realistically compete to become the government because of the weakness of other parties
• multi-party system - when more than two parties can realistically compete to become the government

See also

• List of democracy and elections-related topics