A Member of Parliament is a representative of the voters to a parliament. In many countries with bicameral parliaments, the term applies specifically to members of the lower house, as upper houses often have a different title, such as senate, and thus also have different titles for its members, such as "senators".

Members of parliament tend to form parliamentary groups (also called parliamentary parties) with members of the same political party. In everyday use, the term Member of Parliament is almost always shortened to the initialism "MP", and this is also common in the media.

In Australia, the term "MP" refers to a Member of the House of Representatives, the lower house of the Commonwealth (i.e. federal) parliament. Members may use "MP" after their names; "MHR" is not used, although it was used as a post-nominal in the past. A member of the upper house of the Commonwealth parliament, the Senate, is known as a "Senator".

In the Australian states of New South Wales and Victoria, a Member of the Legislative Assembly (lower house) may also use the post-nominal "MP". Members of the Legislative Council (upper house) use the post-nominal "MLC".

David William Donald Cameron (pronunciation: /ˈkæmərən/; born 9 October 1966) is the Prime Minister of the United Kingdom, First Lord of the Treasury, Minister for the Civil Service and Leader of the Conservative Party. He represents Witney as its Member of Parliament (MP).

Cameron studied Philosophy, Politics and Economics (PPE) at Oxford, gaining a first class honours degree. He then joined the Conservative Research Department and became Special Adviser to Norman Lamont, and then to Michael Howard. He was Director of Corporate Affairs at Carlton Communications for seven years.

He was defeated in his first candidacy for Parliament at Stafford in 1997, but was elected in 2001 as the Member of Parliament for the Oxfordshire constituency of Witney. He was promoted to the Opposition front bench two years later, and rose rapidly to become head of policy co-ordination during the 2005 general election campaign. With a public image of a youthful, moderate candidate who would appeal to young voters, he won the Conservative leadership election in 2005.