A meeting in 1961 set up the criteria for NAM membership. It ruled that member countries could not be involved in alliances or defence pacts with the main world powers. In this way the NAM sought to prevent its members from becoming pawns in Cold War power games and distanced itself from the Western and Soviet power blocs.
The first summit of NAM heads of state took place in the Yugoslav capital Belgrade in 1961 at the instigation of Yugoslav President Tito. Twenty-five countries were represented and the threat of war between the US and the Soviet Union dominated the summit.
The NAM says it aims to protect the right of nations to "independent judgement" and to counter imperialism. The movement is also committed to restructuring the world economic order.
Since the collapse of the Soviet Union, the NAM's preoccupations with global politics and the Cold War have given way to concerns about globalisation, trade and investment, debt, Aids and international crime.
The NAM does not have a constitution or a permanent secretariat. Its highest decision-making body is the Conference of Heads of States or Government, which usually meets once every three years. At this time the post of NAM chair is passed to the host country of the summit.
Cuba took up the chair of the NAM at the September 2006 Havana summit, taking over from Malaysia.
The NAM chair takes on the administrative burden of running the movement. Because much of the NAM's work is undertaken at the United Nations in New York, the chair country's ambassador to the UN is expected to devote time and effort to NAM matters.
The NAM's Co-ordinating Bureau, also based at the UN, is the main instrument for directing the work of NAM task forces, committees and working groups.
The NAM says all its members have a decision-making role, regardless of size or influence.
The NAM's relevance since the collapse of the Soviet Union has been questioned, with some commentators saying the organisation has outlived its usefulness.
In 2003, Thabo Mbeki, president of South Africa - the NAM chair country at the time - warned that the movement's future depended on its response to global challenges. He called on the NAM to take stronger resolutions on issues of concern.
With its diverse membership, consensus-building is no easy task in the NAM. Some members, including India and Pakistan, have been at loggerheads for years.