Watch the Section 3: The Lydian Mode online guitar lesson by Robbie Calvo from Power Play: Major
The Lydian mode is the fourth mode of the major scale and relates directly to the fourth chord built off the 4th degree of the major scale. The chord built off the 4th degree of the major scale is a major 7th chord. We can add extensions to this chord of a 9th, #11 and 13th. Now, when you create a chord progression that resolves to the 4th chord in the major scale it is a Lydian progression and you can use the Lydian mode to improvise over that progression. The characteristic note of Lydian is the #11 (#4). Targeting this note will produce more of the Lydian characteristic sound. It has a little dissonance to it which many guitarists favor to add some spice to their improvisations. Let's check out the Lydian keys you'll be playing over.