ITF is the International Taekwon-Do Federation, founded on March 22nd, 1966, by General Choi Hong Hi, who developed Taekwon-Do, to promote the teaching of this martial art. At that time, nine countries were involved: Korea, Vietnam, Malaysia, Singapore, West Germany, USA, Turkey, Italy, and Egypt. Taekwon-Do is now taught in almost every country in the world, and General Choi is recognized as the Father of Taekwon-Do.
One thing to note. Taekwondo practitioners usually always wear the pull-over style uniforms with the v-neck, however the ITF organization practices with the more traditional open uniform similar to that of Karate.