13.41Extensions are color, not function

This is one of the most important ideas in this module.

Compare:

G7

G9

G13

G7♭9

All may have the same basic function:

dominant of C.

Their colors differ.

So first think:

function = V7

then:

color = 9 / 13 / ♭9 / etc.

Do not let the long chord symbol obscure the simple harmonic job.