The Westminster system is a democratic

Democracy

Democracy is generally defined as a form of government in which all adult citizens have an equal say in the decisions that affect their lives. Ideally, this includes equal participation in the proposal, development and passage of legislation into law...

 parliamentary system

Parliamentary system

A parliamentary system is a system of government in which the ministers of the executive branch get their democratic legitimacy from the legislature and are accountable to that body, such that the executive and legislative branches are intertwined....

 of government

Government

Government refers to the legislators, administrators, and arbitrators in the administrative bureaucracy who control a state at a given time, and to the system of government by which they are organized...

 modelled after the politics of the United Kingdom

Politics of the United Kingdom

The politics of the United Kingdom takes place within the framework of a constitutional monarchy, in which the Monarch is the head of state and the Prime Minister of the United Kingdom is the head of government...

. This term comes from the Palace of Westminster

Palace of Westminster

The Palace of Westminster, also known as the Houses of Parliament or Westminster Palace, is the meeting place of the two houses of the Parliament of the United Kingdom—the House of Lords and the House of Commons...

, the seat of the Parliament of the United Kingdom

Parliament of the United Kingdom

The Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body in the United Kingdom, British Crown dependencies and British overseas territories, located in London...

.

The system is a series of procedures for operating a legislature

Legislature

A legislature is a kind of deliberative assembly with the power to pass, amend, and repeal laws. The law created by a legislature is called legislation or statutory law. In addition to enacting laws, legislatures usually have exclusive authority to raise or lower taxes and adopt the budget and...

. It is used, or was once used, in the national legislatures and subnational

Administrative division

An administrative division, subnational entity, or country subdivision is a portion of a country or other political division, established for the purpose of government. Administrative divisions are each granted a certain degree of autonomy, and are required to manage themselves through their own...

 legislatures of most Commonwealth

Commonwealth of Nations

The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...

 and ex-Commonwealth nations upon being granted responsible government

Responsible government

Responsible government is a conception of a system of government that embodies the principle of parliamentary accountability which is the foundation of the Westminster system of parliamentary democracy...

, beginning with the first of the Canadian provinces in 1848 and the six Australian colonies between 1855 and 1890.

There are other parliamentary systems whose procedures differ considerably from the Westminster system.
Important features of the Westminster system include the following, although not all of the following aspects have been preserved in every Westminster-derived system:

• a sovereign
  Sovereignty
  Sovereignty is the quality of having supreme, independent authority over a geographic area, such as a territory. It can be found in a power to rule and make law that rests on a political fact for which no purely legal explanation can be provided...
  
   or head of state
  Head of State
  A head of state is the individual that serves as the chief public representative of a monarchy, republic, federation, commonwealth or other kind of state. His or her role generally includes legitimizing the state and exercising the political powers, functions, and duties granted to the head of...
  
   who is the nominal or legal and constitutional holder of executive power, and holds numerous reserve power
  Reserve power
  In a parliamentary or semi-presidential system of government, a reserve power is a power that may be exercised by the head of state without the approval of another branch of the government. Unlike a presidential system of government, the head of state is generally constrained by the cabinet or the...
  
  s, but whose daily duties mainly consist of performing ceremonial functions.