Guido of Arezzo was a monk who lived from 991 to about 1033 CE. He contributed to musical notation creating a system of hexacords. In order to help teach Guido´s system, his students developed the Guidonian hand. Each joint of the hand represented a different solfège syllable, in a different hexacord, so techers would point to different joints in their hands and have their students sing the intervals. This became the most common way to tech singing, through the use of the Guidonian hand.
