Watch the Maj. Triad: Lydian Sound online guitar lesson by Kenny Wessel from Shades of Jazz
Let's listen to a Gmaj7 vamp. I'm going to improvise using an A triad over it. This will give us the upper intervals of the chord: 9, #11 and 13. Then later in the track you'll hear me play a G major triad to illustrate the differences of chord tones (1, 3, 5) versus colors.