A diatonic scale is a scale comprising of seven tones. A common diatonic scale is the first (or "Ionian") mode of the Major scale and can be considered one of the major building blocks of western tonal music. "Diatonic" can also be taken to refer to being "in a key"; i.e. pertaining to any non-synthetic scale.
As the only fundamental characteristic of the diatonic scale is to have seven tones, many different types of diatonic scales may be constructed. However, the basic and most familiar diatonic scales are the major scale and minor scale. Below, a major scale on C, followed by a natural minor scale on A:
\meterOff \cadenzaOn c d e f g a b c \bar "||" a, b c d e f g a</music>