Ionian (Major)
The major scale — the most familiar sound in Western music
Ionian is the major scale — the most familiar and foundational major major mode, and the most common scale in Western music. Bright, resolved, and stable: the default sound of nursery rhymes and most pop and rock. Its major pentatonic subset is the innate human melodic scale.
The major scale prevails over non-diatonic scales because of its internal consonance and its versatile containment of triads, tetrads, and pentatonics. It prevails over the other major modes because its single dominant 7th chord, on the 5th degree, resolves strongly to the root — in the other modes that resolution does not land on the root.
Common in pop, rock, classical, country, folk, gospel, Broadway, and film scores. The overwhelming majority of popular music is in Ionian or its relative Aeolian.