The dominant 7th chord is used a lot in blues and country music, so if you enjoy either of those types of music, pay attention on this one!
Normal guitar chords only need three notes to be considered a chord, and as such are called triads. However, the dominant 7th chord is a four note chord, which makes it a tetrachord. That’s just a fancy way of saying it has four notes.
In the lesson, Colin uses a 12 bar blues example in G, and if you want to solo over that progression, you should use the G pentatonic minor scale.
In the blues, the dominant 7th chord is often substituted instead of a minor chord, although many songs have used it to substitute for major chords.
Learn the Dominant 7th Chord:
Watch the lesson on Youtube.