The Cm7♭5 chord (half-diminished): notes C D# F# A#, degrees 1 – ♭3 – ♭5 – ♭7. Guitar shapes: x31312, x34346, x3434x, 8-9-8-8-11-8.
A chord is the root plus degrees above it, most often stacked in thirds. Major and minor differ only in the lower third: a major third (M3) sounds bright, a minor third (m3) sounds sad. Pick a chord and a root to see its degrees and intervals, and its shapes.
m — minor, M — major, P — perfect, A — augmented interval; the number is the degree count. m3 is 3 semitones, M3 is 4, P5 is 7
C Cm C5 C7 Cm7 Cmaj7 Csus2 Csus4 Cadd9 C6 Cm6 C9 Cdim Cdim7 Cm7♭5 Caug