What new musical form developed Around the year 1100?

Around the year 1100, the new musical form known as "organum" developed. This early polyphonic style involved adding one or more voices to a plainchant melody, creating harmonic depth. Organum laid the groundwork for the later development of more complex polyphony and was significant in the evolution of Western music. It marked a shift from monophonic chant to more intricate musical textures.