The Dorian Mode is a minor type of scale. It is a very widely used scale across multiple genres and often associated with blues and jazz guitar playing. The Dorian Mode is the second of the seven major musical modes.
It is a minor type scale because it as a b3 (minor third) but unlike the Natural Minor scale, it has a major 6th note giving it its very distinctive sound. It gives it a mystical and sweet touch.
To play a Dorian scale you would play a major scale starting from its 2nd degree (2nd note). For example, to play a D Dorian scale you would play a C Major scale starting from the D note.
The intervals are:
1-1/2-1-1-1-1/2-1
This gives the following scale degrees:
R-2-b3-4-5-6-b7
Here are the common Dorian Mode patterns for guitar:
*(R) stands for Root or the first note of the scale.