The United Nations (UN) is a complex global organization with a multifaceted structure designed to address a wide range of international issues. Understanding its principal organs is fundamental for anyone interested in global governance and international relations, especially for competitive examinations.

The UN Charter establishes six principal organs, each with distinct roles and responsibilities. These organs form the backbone of the UN's operations and are crucial for its mandate of maintaining international peace and security, developing friendly relations among nations, and achieving international cooperation.

Often referred to as the 'parliament of the world,' the General Assembly is the main deliberative, policymaking, and representative organ of the UN. It provides a unique forum for all 193 Member States to express their views on the full spectrum of international issues covered by the Charter.

The Security Council has the primary responsibility for the maintenance of international peace and security. It can investigate any dispute or situation that might lead to international friction and can recommend methods of adjustment or terms of settlement.

ECOSOC is the principal body for coordination, policy review, policy dialogue, and recommendations on economic, social, and environmental issues, as well as for the implementation of the internationally agreed-upon development goals. It serves as the central platform for UN system-wide discussion and innovative thinking on sustainable development.

The International Court of Justice, located in The Hague, Netherlands, is the principal judicial organ of the United Nations. Its main function is to settle, in accordance with international law, legal disputes submitted to it by States and to give advisory opinions on legal questions referred to it by authorized United Nations organs and specialized agencies.

The Secretariat comprises the Secretary-General and the international staff that work for the UN. It is responsible for the day-to-day administration of the UN's vast work program, servicing the other organs, and implementing their decisions.

The Trusteeship Council was established to provide international supervision for 11 Trust Territories that had been placed under the administration of seven Member States and to ensure that they were administered in the best interests of their inhabitants and in the interests of international peace and security. By 1994, all Trust Territories had attained self-government or independence.

Beyond the six principal organs, the UN system includes numerous specialized agencies, funds, and programs that work on specific issues such as health, education, labor, and environmental protection. These entities are often autonomous but are linked to the UN through agreements and coordinate their efforts through ECOSOC and the Administrative Committee on Coordination.