A scale is a group of musical notes arranged in ascending and descending order. Music scales define which notes are used and how chords are constructed within the key signature. Different scales determine whether or not notes will be played flat or sharp. Music theory scales employ a mathematical system of whole, half and minor third steps that can affect the entire mood of a piece.
A diatonic scale is a seven-note musical scale with seven pitches comprised of five whole steps and two half steps; the half steps are maximally separated. This means that two or three whole steps are between each of the two half steps, and the pattern repeats at the octave. Major and minor scales, which are the foundation of modern music, are diatonic scales. Diatonic scales are also known as the heptatonia prima.
Chromatic scales are musical scales with 12 pitches, in ascending or descending order, each one a half step apart. Unlike the diatonic scale, the notes of chromatic scales are evenly spaced. Derived from the Greek word "chroma," which means color, chromatic notes are not meant to carry the melody, but are rather suited for harmonic flourishing of diatonic notes. Among the chromatic scales are the Pythagorean chromatic scale, the ascending and descending chromatic scales, the harmonic chromatic scale and the melodic chromatic scales.
The melodic scale comprises the notes c, d, e flat, f, g, a and b. Like the diatonic scale, the melodic scale has only two seconds, major and minor seconds. The melodic scale is very familiar in jazz music and is particularly useful in improvisation. There is a melodic major scale and a melodic minor scale.
Harmonic scales are known to have an intense, sometimes off-putting sound and are generally used for emphasis in parts of a song, rather than throughout the entire piece. In a major harmonic scale, the sixth note is flattened by one half step. In a minor harmonic scale, the third and sixth notes are each flattened by one half step. The harmonic scale can be difficult for instrumentalists and singers because the flattened sixth note is highly unusual except in Middle Eastern music.