The term "5음계" refers to the pentatonic scale, a musical scale consisting of five notes per octave. This scale is widely used in various musical traditions around the world, including Korean music, Chinese music, and African music. The simplicity of the pentatonic scale makes it easy to play and sing, often resulting in melodies that are harmonious and pleasing to the ear. In the context of Korean music, the 5음계 is particularly significant, as it forms the basis for many traditional songs and compositions. The scale typically includes the notes that correspond to the first, second, third, fifth, and sixth degrees of the major scale, creating a unique sound that is characteristic of Korean folk music and instruments like the gayageum.