20th Anniversary of UNESCO (Aden 1966)

Stamp 20th Anniversary of UNESCO it reflects the thematic directions:

An anniversary is the date on which an event took place or an institution was founded in a previous year, and may also refer to the commemoration or celebration of that event. For example, the first event is the initial occurrence or, if planned, the inaugural of the event. One year later would be the first anniversary of that event. The word was first used for Catholic feasts to commemorate saints. Most countries celebrate national anniversaries, typically called national days. These could be the date of independence of the nation or the adoption of a new constitution or form of government. The important dates in a sitting monarch's reign may also be commemorated, an event often referred to as a "Jubilee".

The United Nations Educational, Scientific and Cultural Organization (UNESCO; pronounced /juːˈnɛskoʊ/) is a specialized agency of the United Nations (UN) with the aim of promoting world peace and security through international cooperation in education, arts, sciences and culture. It has 194 member states and 12 associate members,as well as partners in the non-governmental, intergovernmental and private sector. Headquartered in Paris, France, UNESCO has 53 regional field offices and 199 national commissions