The Lydian mode is a type of major scale. It is very happy sounding and has a magical and dreamy touch when used in guitar soloing.
It is only one note different from the major scale, it has a sharpened fourth giving it its dreamlike character. It is the 4th of the seven musical modes.
To create a Lydian scale you would play a major scale starting from the 4th note. For example: to play an F Lydian scale you would play a C Major scale from F to F.
The intervals are:

1-1-1-1/2-1-1-1/2

The scale degrees:

R (Root)-2-3-#4-5-6-7

Here are the most common Lydian scale patterns:

*(R) stands for Root or the first note of the scale.