Minor Pentatonic Scale
The 1, 3, 5 and 7 are very strong chord tones, so you can play them confidently, and it will sound good.
The 4 is the only note that doesn't sound very strong or resolved, but you can always bend it up to to the 5.
The fact that 4 out of 5 notes in this scale are strong is what makes it so popular and easy to learn.
