Various other GA commissions, committees, or subsidiary bodies are treaty based, some established by GA resolutions.
More information on subsidiary organs can be found at the UN Web site.
ECOSOC is the principal United Nations body dealing with economic, social, cultural and health issues, as well as human rights and fundamental rights and freedoms. Similar tasks fall to the Regional Economic Commissions.
As the principal judicial organ of the United Nations, the ICJ djudicates legal disputes submitted to it by States and provides opinions on legal questions referred to it by international agencies.
The Secretariat carries out the day-to-day work of the organization, providing services to other principal organs of the UN and administering their programs. It is headed by the Secretary-General.
The Security Council is responsible for the maintenance of international peace and security. The Council has 15 members-- five permanent and 10 elected by the General Assembly for two-year terms.
The Trusteeship Council was the organ of the UN responsible for the administration of territories under the UN Trusteeship system. It ceased operation in 1994, with the independence of Palau, the last remaining UN trust territory.