Prime minister - AbsoluteAstronomy.com

A prime minister is the most senior minister

Minister (government)

A minister is a politician who holds significant public office in a national or regional government. Senior ministers are members of the cabinet....

of cabinet

Cabinet (government)

A Cabinet is a body of high ranking government officials, typically representing the executive branch. It can also sometimes be referred to as the Council of Ministers, an Executive Council, or an Executive Committee.- Overview :...

in the executive

Executive (government)

Executive branch of Government is the part of government that has sole authority and responsibility for the daily administration of the state bureaucracy. The division of power into separate branches of government is central to the idea of the separation of powers.In many countries, the term...

branch 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...

in a 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....

. In many systems, the prime minister selects and may dismiss other members of the cabinet, and allocates posts to members within the government. In most systems, the prime minister is the presiding member and chairman of the cabinet. In a minority of systems, notably in semi-presidential system

Semi-presidential system

The semi-presidential system is a system of government in which a president and a prime minister are both active participants in the day-to-day administration of the state...

s of government, a prime minister is the official who is appointed to manage the civil service

Civil service

The term civil service has two distinct meanings:* A branch of governmental service in which individuals are employed on the basis of professional merit as proven by competitive examinations....

and execute the directives of the 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...

.

In parliamentary systems fashioned after the Westminster system

Westminster System

The Westminster system is a democratic parliamentary system of government modelled after the politics of the United Kingdom. This term comes from the Palace of Westminster, the seat of the Parliament of the United Kingdom....

, the prime minister is the presiding and actual head of the government and head of the executive branch.