The A#9 chord (dominant 9th): notes A# D F G# C, degrees 1 – 3 – 5 – ♭7 – 9. Guitar shapes: x10111, 633334, 65656x, 686768.
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
A# A#m A#5 A#7 A#m7 A#maj7 A#sus2 A#sus4 A#add9 A#6 A#m6 A#9 A#dim A#dim7 A#m7♭5 A#aug