Solfege is a method of assigning syllables to musical pitches, making them easier to sing. It originated with Guido d'Arezzo in the 11th century and uses syllables like "do re mi fa so la ti do." There are two systems - movable "do," where do shifts with key, and fixed "do," where do is always C. Learning solfege improves sight singing, transcription, relative pitch, and composing by helping recognize patterns in music.