Introduction to the Diatonic Scale
The Diatonic scale is also known as the major scale and the (natural) minor scale.
The diatonic scale contains seven notes.
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The diatonic scale is nothing more than these seven notes mapped out across your entire guitar.
For ease of communication, the ESG method for learning guitar has assigned a name to each of the five basic scale shapes.
Notice that Diatonic Scale (red+black) is simply the Pentatonic Scale (red) with extra notes.