The Phryhian mode is an exotic sounding scale frequently associated with Spanish and Flamenco music. It has a very distinctive eastern vibe to it. It is also regularly used by metal guitar players because of the dark atmosphere it can create.

Phrygian is the third degree of the major scale. It is a type of minor scale because it has a b3 (minor third). It also has a flattened 2nd giving it its dark and mystical vibe.

To create a Phrygian scale you would start playing a Major scale from its third note. For example: To play an E Phrygian scale you would play a C Major scale starting from E going to the E.

The intervals are:
½-1-1-1-½-1-1

The degrees are:
R (Root)-b2-b3-4-5-b6-b7

Here are the common patterns for the Phrygian mode on guitar:

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