The best guitar scale to learn if you are into Rock music is the Pentatonic scale. The Pentatonic scale is also used in many other types of popular music, like Blues for example.
The Pentatonic scale has 5 notes that create 5 patterns that connect across the entire fretboard. These 5 patterns get their names from the notes that are in the scale... Root, 2nd, 3rd, 5th and 6th. Also, just by adding a few notes, you can create all of your other scales just by using this one pattern. You start off by using the Pentatonic to visualize your scales and then you add a note or two and you can play over top of any chords.
Here is the Pentatonic scale 6th shape that you will want to memorize first:
The Pentatonic scale has 5 notes that create 5 patterns that connect across the entire fretboard. These 5 patterns get their names from the notes that are in the scale... Root, 2nd, 3rd, 5th and 6th. Also, just by adding a few notes, you can create all of your other scales just by using this one pattern. You start off by using the Pentatonic to visualize your scales and then you add a note or two and you can play over top of any chords.
Here is the Pentatonic scale 6th shape that you will want to memorize first:
