When the intervals are arranged in the ascending order of their ratios, it produces the eight white notes of the major scale: The Diatonic scale.

This seventh interval is essential when we examine chords formed with four notes. These chords are known as seventh chords.

There are two semitones spanning the notes of a major second interval. This major second distance between the root and second notes of chords are known as suspended chords.

The chord at the sixth position progresses most harmoniously to the perfect fourth and forms part of chord progressions for a disproportionally large number of classic hits.

The interval between the fifth harmonic (5X) and the sixth harmonic (6X) gives the minor third interval. This interval also covers three white positions of the C major scale but is one semitone smaller than the major third shown above.

The interval between the fourth harmonic (4X) and the fifth harmonic (5X) gives the major third interval. The interval covers three white positions of the C major scale. Four semitones span the notes of a major third interval.

A perfect fourth above the Tonic is the perfect fourth and a perfect fourth below the Tonic is a perfect fifth. The Tonic, the Dominant (perfect fifth), and the Sub Dominant (perfect fourth) are the foundation on which harmony in Western music is constructed.

The perfect fifth is the second most important interval in music after the octave. When we examine chords, you will see that most harmony chords have this interval between their root and third notes.

The octave is the most important interval in music as it is the same note at double the frequency. When any note and its octaves are played together, the note sounds deeper and more robust.

Intervals describe the relationship between the pitch of two notes. They are the language of music communication. For scales, intervals are usually described in semitones and tones.