key signature
B major
B1C♯2D♯3E4F♯5G♯6A♯7
5 sharps, written F♯ C♯ G♯ D♯ A♯
The chords that live in it
Bdegree 1 · majorC♯mdegree 2 · minorD♯mdegree 3 · minorEdegree 4 · majorF♯degree 5 · majorG♯mdegree 6 · minorA♯dimdegree 7 · diminished
Built by stacking thirds inside the scale and asking what quality comes out, rather than from a table of roman numerals.
What is true of it
B major has 5 sharps.
They are written in this order, always: F♯ C♯ G♯ D♯ A♯.
Its notes are B, C♯, D♯, E, F♯, G♯ and A♯.
Relative: G♯ minor has the same 5 sharps. Parallel: B minor has 2 sharps, which is why changing mode changes the signature by three.
Every key
C♭ majorG♭ majorD♭ majorA♭ majorE♭ majorB♭ majorF majorC majorG majorD majorA majorE majorF♯ majorC♯ majorA♭ minorE♭ minorB♭ minorF minorC minorG minorD minorA minorE minorB minorF♯ minorC♯ minorG♯ minorD♯ minorA♯ minor