So far, everything has been discussed in terms of major keys. However, there is another common type of key called a minor key. Minor keys are often described as having a "sadder" sound than major keys. Songs in a minor key use notes taken from a minor scale. There are several types of minor scales. The three most common are the natural minor, the harmonic minor and the melodic minor. Each one has its own distinctive pattern of tones and semitones. Here are the three A minor scales, along with the appropriate pattern of tones and semitones. The degrees of each scale as they would relate to the major scale are written under the note names.
Notice the distance of 1p tones (three semitones) between the 6th and 7th degrees of the harmonic minor scale. This scale is often described as having an "Eastern" sound.
In Classical music the 6th and 7th notes of the melodic minor scale are sharpened when ascending and returned to natural when descending. However, in Jazz and other modern styles, the melodic minor descends the same way it ascends. An easy way to think of this scale is as a major scale with a flattened third degree.