Pentatonic Minor Scale
The first scale most guitar players learn is the pentatonic minor scale. Its easy shape, ease of use, and applicability to many genres make it a perfect first tool for the tool belt. To give context, the natural minor scale is also included for comparison.
The A Pentatonic Minor Scale is constructed with the 1, b3, 4, 5, and b7 notes of the major scale. It has just 5 notes, which is where "pent"atonic comes from, "pent" meaning 5.