key signature
E major
E1F♯2G♯3A4B5C♯6D♯7
4 sharps, written F♯ C♯ G♯ D♯
The chords that live in it
Edegree 1 · majorF♯mdegree 2 · minorG♯mdegree 3 · minorAdegree 4 · majorBdegree 5 · majorC♯mdegree 6 · minorD♯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
E major has 4 sharps.
They are written in this order, always: F♯ C♯ G♯ D♯.
Its notes are E, F♯, G♯, A, B, C♯ and D♯.
Relative: C♯ minor has the same 4 sharps. Parallel: E minor has 1 sharp, which is why changing mode changes the signature by three.
Every key
C♭ majorG♭ majorD♭ majorA♭ majorE♭ majorB♭ majorF majorC majorG majorD majorA majorB majorF♯ majorC♯ majorA♭ minorE♭ minorB♭ minorF minorC minorG minorD minorA minorE minorB minorF♯ minorC♯ minorG♯ minorD♯ minorA♯ minor