The existence of international days predates the establishment of the United Nations, but the UN has embraced them as a powerful advocacy tool. The United Nations observes designated days, weeks, years, and decades, each with a theme, or topic. By creating special observances, the United Nations promotes international awareness and action on these issues. Each international day offers many actors the opportunity to organize activities related to the theme of the day. Organizations and offices of the United Nations system, and most importantly, governments, civil society, the public and private sectors, schools, universities and, more generally, citizens, make an international day a springboard for awareness-raising actions. The majority of observances have been established by resolutions of the United Nations General Assembly, although some have been designated by UN specialized agencies. The United Nations also observes anniversaries of key events in its history.