Since the early days of the United Nations system, the UN has established a set of Days and Weeks (as listed below), Years and Decades to help focus the world on the issues in which the UN has an interest and commitment. The UN calls on Member States and other organizations to mark these days in ways which reflect their priorities.
Sometimes the promotion of a specific day is led by a specific UN agency or programme, for example the World Health Organization (WHO) leads World Health Day and World No-Tobacco Day, UN Educational Scientific and Cultural Organization (UNESCO) leads World Water Day and International Literacy Day, UN Environment Programme (UNEP) leads World Environment Day etc.
Some UN agencies also have their own international days (e.g. WHO's World TB Day and UNESCO's World Philosophy Day), established and promoted by the agency but not designated by the UN General Assembly for the full UN system. While equivalent in purpose, the following list does not include agency-specified days.