Pentatonic scale

The pentatonic scale has only five notes per octave (versus seven for a standard major or minor scale) — the name comes from the Greek penta, five. Removing two notes from the natural minor scale eliminates the half-step intervals, widely considered the hardest for a beginner to place accurately by ear.

That's why the pentatonic scale is almost always the first improvisation tool taught on guitar: on any note of the box, nothing sounds glaringly "wrong", unlike a seven-note scale where certain degrees need careful handling depending on the underlying chord.

The trade-off the pentatonic scale rarely admits to

This tolerance has a rarely-explained downside: the pentatonic scale works almost everywhere precisely because it's less harmonically precise than a full scale — it dodges tension rather than resolving it. The same position 1 of the E minor pentatonic scale works equally well over a blues progression or a metal riff in Guitarshelf's catalog, whereas a full major scale wouldn't suit both.