The International Telecommunication Union is the second-oldest international organization still in existence (the oldest being the Rhine Commission), established to standardize and regulate international radio and telecommunications. It was founded as the International Telegraph Union in Paris on 17 May 1865. Its main tasks include standardization, allocation of the radio spectrum, and organizing interconnection arrangements between different countries to allow international phone calls — in which regard it performs for telecommunications a similar function to what the UPU performs for postal services. It is one of the specialized agencies of the United Nations, and has its headquarters in Geneva, Switzerland, next to the main United Nations campus.

The ITU was the lead organizing agency of the World Summit on the Information Society (WSIS), a United Nations summit aiming at bridging the digital divide and turning it into digital opportunity for all. WSIS provided a global forum on the theme of ICTs (Information and Communication Technologies) for development, involving for the first time all stakeholders - governments, international organizations, civil society and business. WSIS was a pledge for building a people-centered development-oriented Information Society. Other big themes of the Summit were Internet governance and Financial mechanisms for meeting the challenges of ICTs for development.

The ITU is made up of three sectors:

• The Telecommunication Standardization Sector, ITU-T, whose secretariat is the Telecommunication Standardization Bureau or TSB, known prior to 1992 as the International Telephone and Telegraph Consultative Committee or CCITT (from its French name "Comité consultatif international téléphonique et télégraphique");
• The Radiocommunication Sector, ITU-R, whose secretariat is the Radiocommunication Bureau or BR, known prior to 1992 as the International Radio Consultative Committee or CCIR (from its French name "Comité consultatif international des radiocommunications");
• The Telecommunication Development Sector, ITU-D, whose secretariat is the Telecommunication Development Bureau or BDT, created in 1992.

A permanent General Secretariat, headed by the Secretary General, manages the day-to-day work of the Union and its sectors.