Understanding guitar scales and modes is very important if you really want to advance your guitar skills. Learning the 7 modes of the major scale, the basis of Western music, and becoming comfortable with the different scale patterns will enable you to make up your own riffs and solos across the entire fretboard, which is what separates a beginner from an advanced player. Learning scales will also make understanding chord much easier, so don't hesitate.
The most important step you can take in learning scales is learning the major scale and its note intervals. Why? Because the 7 modes all start off of a given note of the original major scale, which makes remembering their note patterns much easier.
First of all, we need to define what a scale actually is. A scale is a series of notes with predefined intervals, starting off of a root note, and ending on the same note one octave higher. As you know, music has the ability to impact our emotions and mood. The interval pattern of scales will define its mood and style, ranging from happy and upbeat (Ionian mode), to sad (Aeolian mode), to sinister (Locrian mode).
Now that we know what scales are, lets have a look at the 7 guitar modes which are most used in Western music. Note: "W" means 2 semitones, "H" means 1 semitone between each scale note.
Ionian Mode (the Major Scale itself)
Note intervals: W-W-H-W-W-W-H
Mood: Happy
Musical styles: country, jazz, rock
Dorian Mode (roots on the second note of the major scale)
Note intervals: W-H-W-W-W-H-W
Mood: Jazzy
Musical styles: rock, country, jazz
Phrygian Mode (roots on the third note of the m. scale)
Note intervals: H-W-W-W-H-W-W
Mood: Spanish
Musical styles: flamenco, Spanish guitar
Lydian Mode (roots on the fourth note of the m. scale)
Note intervals: W-W-W-H-W-W-H
Mood: mesmerizing, dreamy
Musical styles: jazz, country, rock
Mixolydian Mode (roots on the fifth note of the m. scale)
Note intervals: W-W-H-W-W-H-W
Mood: Blues
Musical styles: blues, rockabilly, country
Aeolian Mode (also known as the minor scale, it roots on the sixth note of the m. scale)
Note intervals: W-H-W-W-H-W-W
Mood: sad
Musical styles: pop, blues, metal, rock, country
Locrian Mode (roots on the second note of the m. scale)
Note intervals: H-W-W-H-W-W-W
Mood: sinister, horrifying
Musical styles: jazz, fusion
Modal theory is actually pretty simple, once you understand the relationship between the different scale modes. Once you learn the scale patterns and the notes on the fretboard, you'll be able to play solos and make up your own riffs all over the neck of the guitar, which feels great and will really impress others.
