Mixolydian

The notes

B C♯ D♯ E F♯ G♯ A, then B. It is the fifth mode of E major and shares its four sharps. The A natural in place of A♯ is the single difference from B major.

Because E major is the guitar’s most resonant key, this mode inherits a good deal of that comfort: the notes fall where the hand already knows them.

On the fretboard

Seventh fret with the root on the low E string, or second fret with the root on the A. The seventh-fret position is standard, and it overlaps with the B minor pentatonic that most players use for solos.

The A natural is the note that must sound. Without it the scale is plain B major, and over a B7 chord that difference is immediately audible.

Where it is used

Over the V chord in E major — which on guitar means a great deal of blues, rock and country. B7 is the turnaround chord in the key the instrument favours most.

It also appears in songs that sit on B7 without resolving, a device common in shuffle and boogie where the harmony is deliberately static.

For a guitarist the mode is worth learning as a pair with E major. Almost every song that uses it is in E, and recognising that B7 wants this scale rather than B major saves a good deal of guessing.