The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications and Information Communication Technology such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPEG-4 AVC for video compression, between its Member States, Private Sector Members, and Academia Members. ITU-T is one of the three Sectors (divisions or units) of the International Telecommunication Union (ITU).

The standardization efforts of ITU started in 1865 with the formation of the International Telegraph Union (ITU). ITU became a Specialized agency of the United Nations in 1947. The International Telegraph and Telephone Consultative Committee (French: Comité Consultatif International Téléphonique et Télégraphique, CCITT) was created in 1956, and was renamed ITU-T in 1993.

ITU-T has a permanent secretariat, the Telecommunication Standardization Bureau (TSB), based at the ITU headquarters in Geneva, Switzerland. The current director of the bureau is Chaesub Lee, whose first 4-year term commenced on 1 January 2015, and whose second 4-year term commenced on 1 January 2019. Chaesub Lee succeeded Malcolm Johnson of the United Kingdom, who was director from 1 January 2007 until 31 December 2014.