key signature
F♯ major
F♯1G♯2A♯3B4C♯5D♯6E♯7
6 sharps, written F♯ C♯ G♯ D♯ A♯ E♯
The chords that live in it
F♯degree 1 · majorG♯mdegree 2 · minorA♯mdegree 3 · minorBdegree 4 · majorC♯degree 5 · majorD♯mdegree 6 · minorE♯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
F♯ major has 6 sharps.
They are written in this order, always: F♯ C♯ G♯ D♯ A♯ E♯.
Its notes are F♯, G♯, A♯, B, C♯, D♯ and E♯.
Relative: D♯ minor has the same 6 sharps. Parallel: F♯ minor has 3 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 majorB majorC♯ majorA♭ minorE♭ minorB♭ minorF minorC minorG minorD minorA minorE minorB minorF♯ minorC♯ minorG♯ minorD♯ minorA♯ minor