A minister is a politician who heads a government department,^[1][2] making and implementing decisions on policies in conjunction with the other ministers. In some jurisdictions the head of government is also a minister and is designated the ’prime minister’, ‘premier’, ’chief minister’, ’chancellor’ or other title.

In Commonwealth realm jurisdictions which use the Westminster system of government, ministers are usually required to be members of one of the houses of Parliament or legislature, and are usually from the political party that controls a majority in the lower house of the legislature. In other jurisdictions — such as Belgium, Mexico, Netherlands, Philippines, Slovenia — the holder of a cabinet-level post or other government official is not permitted to be a member of the legislature. Depending on the administrative arrangements in each jurisdiction, ministers are usually heads of a government department and members of the government's ministry, cabinet and perhaps of a committee of cabinet. Some ministers may be more senior than others, and some may hold the title ’assistant minister’ or ‘deputy minister’. Some jurisdictions, with a large number of ministers, may designate ministers to be either in the inner or outer ministry or cabinet.

In some jurisdictions — such as Hong Kong, the Philippines, the United Kingdom, and the United States — holders of an equivalent cabinet-level post are called secretaries (e.g., the Home Secretary in the United Kingdom, Secretary of State in the United States). Some holders of a cabinet-level post may have another title, such as ’Attorney-General’ or ’Postmaster-General’.

The term "minister" also is used in diplomacy, for a diplomat of the second class, such as in the title Minister Plenipotentiary, ranking between an Ambassador and a Minister Resident.

The term minister comes from Middle English, deriving from the Old French word ministre, originally minister in Latin, meaning "servant, attendant", which itself was derived from the word 'minus' meaning "less".^[3]

In jurisdictions that use the Westminster system of government — such as the United Kingdom and Australia — ministers or their equivalents are selected from the legislature, and usually from the political party that controls a majority in the lower house of the legislature. In jurisdictions with strict separation of powers, ministers cannot be members of the legislature — such as Belgium, Mexico, Netherlands, Philippines, United States — and a legislator chosen to become a minister must resign from the legislature.

Normally the leader of the majority party becomes the prime minister, or an office of equivalent function, and selects the other ministers. In the Westminster system, these ministers continue to represent their constituency in parliament while being part of the government. Often, a person from the outside may be appointed minister, usually in order to bring special skills to the government. Such a person would not have to be part of the parliament while serving as minister, nor would he/she necessarily be a member of the party/parties in government.

Various countries form ministries as Cabinets (see List of cabinets). Other cabinets are usually included in Politics of ..-articles

Specific ministers include:

Some ministers may hold multiple portfolios and lead several ministries simultaneously, while multiple ministers with separate portfolios may oversee a single ministry, or may also share both ministerial and deputy-ministerial portfolios in different ministries. A cabinet minister may not be in charge of any ministry, and is then known as a "minister without portfolio".