https://www.musical-u.com/learn/and-three-makes-triad-hearing-triads/
Triads are the basic form of chords, and can be combined to create harmonies and harmonic progressions.
Learning to distinguish between different types of chords is immensely beneficial for improvising and hearing backing harmonies.
https://www.musical-u.com/learn/and-three-makes-triad-hearing-triads/