Administrative Structure:
i) The executive wing of the United Nations is the UN Secretariat.
ii) It is headed by Secretary General. He is elected by the General Assembly on the recommendation of the Security Council.
iii) The Secretary General along with his cabinet and other officials runs the United Nations.
iv) The International Court of Justice, headquartered at the Hague in Holland. It is the judicial wing of the United Nations.
v) The Economic and Social Council (ECOSOC), is responsible for coordinating all economic and social work of the United Nations
Other Important Organs of the UN:
i) Food and Agriculture Organisation (FAO).
ii) World Health Organisation (WHO),
iii) UN Educational, Scientific and Cultural Organisation (UNESCO)
iv) UNICEF (United Nations Children's Fund)
v) UNDP (United Nations Development Programme)
Activities of the UN:
i) The United Nations has expanded its activities in response to the changing problems facing the world.
ii) Thus, in the 1960s, decolonization was an important issue.
iii) Human rights, the problem of refugees, climate changes, gender equality are all now within the ambit of the activities of the United Nations.
iv) The UN peace keeping force has acted many areas of conflict all over the world. The Indian army has an important part in the peace keeping force. It has served in many parts of the world
v) Poor countries and developing countries are given financial assistance by the UNO.

i) World War II began in 1939 and ended in 1945.
ii) In World War II, had an extensive area of conflict and very high death toll of civilians as well as armed combatants.
New geo-political power Alignment:
i) The world was polarized into two main blocs led by superpowers:
a) United States (Anti communist ideology)
b) Soviet Russia (Communist ideology)
ii) Europe was divided into,
a) Communist
b) Non-Communist
Nuclear Proliferation:
i) The United States and the Soviet Union entered into a race to have more nuclear powered weapons. They built a large stockpile of such weapons.
ii) Defence spending sky-rocketed in many countries.
International Agencies:
i) Many international agencies, in particular the United Nations, the World Bank and the International Monetary Fund came into existence providing a forum for countries large and small.
Social and Economic changes:
i) Social and Economic changes took place in the post-war world.
ii) Colonial powers were forced to give independence to former colonies in a process of decolonization. India was the first to achieve Independence.