The United Nations was founded in 1945 after World War II to promote international cooperation. It has 193 member states and works to address issues like peace and security, sustainable development, human rights, humanitarian aid, and health through various bodies and programs. In 2011, the UN marked its 66th anniversary and continued efforts in areas such as peacekeeping, responding to humanitarian crises, reducing poverty, addressing climate change and the environment, education, and combating HIV/AIDS.