These are the international days currently observed by the United Nations
The United Nations designates specific days, weeks,, years and decades as occasions to mark particular events or topics in order to promote, through awareness and action the objective of the organization. USually it is one or more member states that purpose these observances and the General Assembly establishes them with the resolution.
On occasions these celebrations are decleared by the specialized agencies of the United Nations such as UNSECO, UNICEF, FAO etc. When they concern issues that fall within the scope of their competencies. Some of them may be later adopted by the General Assembly.