There are two or more notes in a chord. Guitar chords usually have three notes... look on wikipedia.com and look up guitar chords or musical chords or somethingPiano chords are usually 3 notes.
The 4 Chords can be the 3 major chords in a key, aka the I IV and V chords and the relative minor aka the vi chord. For the key of C this would be C F G Am. If you know the key, the four chords are...
Every chord is a line on the inside between two points on the circle. A diameter does that, so it's a chord. But in order to be a diameter, a chord also has to meet another requirement ... it has to...