A minister or a secretary is a politician who heads a government ministry or department (e.g. education, finance, health, state, war etc.). Senior ministers are members of the cabinet, usually led by a prime minister or president.
The term "minister" comes from a Latin word meaning a "servant" (or first servant). In some countries (such as the US, Hong Kong, the Philippines and the UK), such a person can instead known as a secretary or secretary of state.
Until the early 20th century, heads of legations were also called ministers, ie: "Minister for Cuba" or "Minister for France." For example, Sir Ernest Satow was Envoy Extraordinary and Minister Plenipotentiary to Japan, 1895-1900, then the top British diplomat in Japan. His successor, Sir Claude MacDonald, was Minister and then Ambassador from 1905 when relations between Britain and Japan were upgraded.
Some examples of ministers, see the lists below for more.
Lists of ministers
See also: Religious minister