The Specialized Agencies are autonomous intergovernmental organizations
linked to the United Nations in accordance with the provisions of Art. 57 and 63 of the Charter. They are separate and independent organizations but cooperate with each other and with the United Nations and they are brought into relationship with the United Nations through special agreements concluded by the ECOSOC. 

The specialized agencies have their own organizational structure, member states, governing bodies, executive heads, and secretariats, and their own budgets. 
Some of the specialized agencies have been in existence long before the United Nations -  the oldest agency is the International Telecommunications Union (ITU), which was founded in 1865. Other agencies have been established much later, the most recent is the World Trade Organization(WTO), founded in 1995.   

The coordination of the specialized agencies towards the UN and among each other is performed by The United Nations System Chief Executives Board for Coordination (CEB) - earlier the  Administrative Committee of Coordination (ACC), composed of the UN Secretary-General as the chairman and
the executive heads of the specialized agencies.

The Joint Inspection Unit (JIU) conducts inspections and investigations of
the efficiency of the UN, its programmes and funds and the specialized agencies. 

The specialized agencies have their own documentation and publishing and depository library system linked to relevant libraries in their member states.