G dominant 7

1. 1

   Root note. The chord takes its name from this degree.

2. 3

   Third. Major or minor quality is decided here.

3. 5

   Fifth. Stable, defines the chord body.

4. b7

   Color tone. Adds character on top of the triad.

The V7 of C major. Use in 12 bar blues, ragtime and any V I cadence.