A parliamentary system, also known as parliamentarianism (and parliamentarism in U.S. English), is distinguished by the executive branch of government being dependent on the direct or indirect support of the parliament, often expressed through a vote of confidence. Hence, there is no clear-cut separation of powers between the executive and legislative branches, leading to a differing set of checks and balances compared to those found in a presidential republic. Parliamentary systems usually have a clear differentiation between the head of government and the head of state, with the head of government being the prime minister or premier, and the head of state often being an elected (either popularly or through parliament) president or hereditary monarch. Though in Parliamentary systems the prime minister and cabinet will exercise executive power on a day-to-day basis, actual authority will usually be bestowed in the head of state, giving them many codified or uncodified reserve powers, providing some balance to these systems.
The term parliamentary system does not mean that a country is ruled by different parties in coalition with each other. Such multi-party arrangements are usually the product of an electoral system known as proportional representation. Parliamentary countries that use first past the post voting usually have governments composed of one party. However, parliamentary systems in continental Europe do use proportional representation, and tend to produce election results in which no single party has a majority of seats.
Parliamentarianism may also be heeded for governance in local governments. An example is the city of Oslo, which has an executive council as a part of the parliamentary system. The council-manager system of municipal government used in some U.S. cities bears many similarities to a parliamentary system.