the.com/triad

Three notes, infinite drama — every chord you've ever hummed hides one inside.

means A group of three closely connected people or things, especially three notes stacked up to form the basic building block of harmony.

from From Greek 'trias' (a group of three), built from 'treis' (three) — the same root behind 'trinity' and 'triangle'. It passed through Latin 'trias/triad-' into English in the 1500s, first used for any threesome of things, before music theory claimed it in the 1600s–1700s for a chord made of a root, third, and fifth stacked together.

root structure
stack two thirds, get one triad
four flavors
major, minor, diminished, augmented, that's it
other meaning
also Chinese organized crime syndicates
inversions
same notes, different bass, different mood
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