The melodic minor is one of the three main kinds of minor scale, the others being the natural minor and the harmonic minor. The melodic minor scale came about because some composers found that, in writing melody lines, the interval of three semitones between the 6th and 7th notes of the harmonic minor scale was unacceptably large. To deal with this, they raised the 6th note of the scale by a semitone. The result is a smoother melodic flow. This method is only used when ascending the scale. Upon descending, it isn't important to have the semitone interval between the 7th and 8th notes, because the melodic flow is naturally smooth. Therefore, the ordinary natural minor scale is used. A well known song that uses the melodic minor is Greensleeves.