key signature
C minor
C1D2E♭3F4G5A♭6B♭7
3 flats, written B♭ E♭ A♭
The chords that live in it
Cmdegree 1 · minorDdimdegree 2 · diminishedE♭degree 3 · majorFmdegree 4 · minorGmdegree 5 · minorA♭degree 6 · majorB♭degree 7 · major
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
C minor has 3 flats.
They are written in this order, always: B♭ E♭ A♭.
Its notes are C, D, E♭, F, G, A♭ and B♭.
Relative: E♭ major has the same 3 flats. Parallel: C major has no sharps and no flats, 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 majorF♯ majorC♯ majorA♭ minorE♭ minorB♭ minorF minorG minorD minorA minorE minorB minorF♯ minorC♯ minorG♯ minorD♯ minorA♯ minor