D Lydian scale on the guitar fretboard
The D Lydian scale is made of D (the root), E (major second), F# (major third), G# (augmented fourth), A (perfect fifth), B (major sixth) and C# (major seventh). The fretboard shows every one of them across the neck in standard tuning (E A D G B E), and plays them back so you can hear the scale.
The Lydian mode is the fourth mode of the major scale, a major scale with a raised fourth. The raised fourth sits a tritone from the root, and the scale shares its notes with a major scale a fifth above. It is the brightest of the seven modes.