The United Nations was created to ensure that governments of major countries around the world would continue to actively fight against the axis powers in World War 2.
The League of Nations came before the United Nations. It was created to provide a forum for resolving international disputes.
The ultimate goal of the United Nations is maintaining international peace and security, developing friendly relations among nations and promoting social progress, better living standards and human rights.
The United Nations Headquarters is located in New York City.
The main organs of the United Nations are the General Assembly, the Security Council, the Economic and Social Council, the Trusteeship Council, the International Court of Justice, and the United Nations Secretariat.
The Security Council is an important division of the United Nations that contains five permanent members — the United States, Britain, China, France, Russia, and ten rotating members.
Countries that are part of the United Nations:
Afghanistan Bhutan Costa Rica Fiji
Albania Bolivia Côte d’Ivoire Finland
Algeria Bosnia and Herzegovina  Croatia  France
Andorra Botswana Cuba Gabon
Angola Brazil Cyprus Gambia
Antigua and Barbuda Brunei Darussalam Czech Republic  Georgia
Argentina Bulgaria Democratic People’s Republic of Korea Germany 
Armenia Burkina Faso Democratic Republic of the Congo  Ghana
Australia Burundi Denmark Greece
Austria Cambodia Djibouti Grenada
Azerbaijan Cameroon Dominica Guatemala
Bahamas Canada Dominican Republic Guinea
Bahrain Cape Verde Ecuador Guinea-Bissau
Bangladesh Central African Republic Egypt  Guyana
Barbados Chad El Salvador Haiti
Belarus  Chile Equatorial Guinea Honduras
Belgium China Eritrea Hungary
Belize Colombia Estonia Iceland
Benin Comoros Ethiopia India
Congo (Republic of the) Mozambique Philippines
Indonesia  Liechtenstein Myanmar Poland
Iran Lithuania Namibia Portugal
Iraq Luxembourg Nauru Qatar
Ireland Madagascar Nepal Republic of Korea
Israel Malawi Netherlands Republic of Moldova
Italy Malaysia  New Zealand Romania
Jamaica Maldives Nicaragua Russian Federation 
Japan Mali Niger Rwanda
Jordan Malta Nigeria Saint Kitts and Nevis
Kazakhstan Marshall Islands Norway Saint Lucia
Kenya Mauritania Oman Saint Vincent and the Grenadines
Kiribati Mauritius Pakistan Samoa
Kuwait Mexico Palau San Marino
Kyrgyzstan Micronesia (Federated States of) Panama Sao Tome and Principe
Lao People’s Democratic Republic Monaco Papua New Guinea Saudi Arabia
Latvia Mongolia Paraguay Senegal
Lebanon Montenegro  Peru Serbia 
Lesotho Morocco Seychelles
Liberia Tonga Sierra Leone
Libya Trinidad and Tobago
Slovakia  Turkey
Slovenia  Turkmenistan
Solomon Islands Tuvalu
South Africa Ukraine
South Sudan United Arab Emirates
Spain United Kingdom
Sri Lanka United of Republic of Tanzania
Sudan United States
Syria  Viet Nam
Tajikistan Yemen 
The former Yugoslav Republic of Macedonia  Zimbabwe
The top 5 countries in the United Nations are the permanent members and decide what happens in the world.
The types of problems consist of safeguarding peace, protecting human rights, establishing the framework for international justice and promoting economic and social progress, in the seven decades since its creation the United Nations has added on new challenges, such as climate change, refugees and AIDS.
First Committee (Disarmament and International Security Committee) is concerned with disarmament and related international security questions
Second Committee (Economic and Financial Committee) is concerned with economic questions
Third Committee (Social, Humanitarian and Cultural Committee) deals with social and humanitarian issues
Fourth Committee (Special Political and Decolonization Committee) deals with a variety of political subjects not dealt with by the First Committee, as well as with decolonization
Fifth Committee (Administrative and Budgetary Committee) deals with the administration and budget of the United Nations
Sixth Committee (Legal Committee) deals with international legal matters
Food aid has been the greatest achievement of the United Nations.
I think it should be kept, because it helps people in need and ends violence in the world.