The World Health Organization (WHO) is a specialized agency of the United Nations that works to promote global public health. It provides leadership on health matters, sets international health standards and guidelines, and monitors health trends worldwide. WHO aims to address major health challenges like achieving the Millennium Development Goals, preventing and treating chronic diseases, and strengthening health systems globally. It carries out its work with support from 193 member states and other partners through activities focused on health development, security, and performance improvement.