Mixolydian mode
A musical mode identical to the major scale but with a lowered seventh degree, producing a bright but slightly bluesy quality.
In Depth
The Mixolydian mode is built on the fifth degree of the major scale — playing all white keys from G to G produces G Mixolydian. Its only difference from the major scale is the flat seventh, which removes the leading tone's pull toward the tonic and gives the mode a relaxed, open-ended quality. The flat seventh creates a natural dominant seventh chord on the tonic, which is why the mode sounds inherently "dominant" and unresolved. Mixolydian is arguably the most important mode in popular music. The entire blues scale is essentially Mixolydian with added chromatic notes, and rock, country, and folk music rely heavily on its character. Classic rock guitar solos often use Mixolydian over dominant seventh chords, and songs from "Norwegian Wood" by The Beatles to "Sweet Home Alabama" by Lynyrd Skynyrd are Mixolydian at their core. In Celtic music, Mixolydian is one of the most common modes, giving Irish and Scottish tunes their characteristic brightness with a hint of wistfulness.
The Mixolydian mode is sometimes called the "rock mode" because its flat seventh gives it the slightly edgy, unresolved quality that defines classic rock guitar playing.