Notes of the scale on which a passage of tonal music is based are called diatonic to distinguish them from the other notes of the chromatic scale. Diatonic is a relative term because a Db, for example, would be diatonic in a passage based on a Db major scale, but chromatic in a passage based on a C major scale.

The major scale is so familiar that it is easy to take it for granted, and comparing it to other scales is a good way of highlighting its properties. The whole-tone scale, for example, is made up of all the same intervals, while the major scale is a mixture of tones and semitones.

The major scale audibly divides the octave into two groups of Tone-Tone-Semitone as shown in the example below. Because the two groups that make up the whole-tone scale consist of three major seconds a major second apart, they do not make the division of the octave audible in the same way. The consequences of this are discussed on page 2 of this section.

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