“Pentatonic” simply means “five tones”, but when you speak of the pentatonic scale, you’re talking about the major scale without the fourth and seventh scale degrees (Fa and Ti). This leaves you with the tonic triad (Do, Mi, So) and the notes a whole step away (Re and La).
The beauty of this scale lies in the total absence of half steps. I’ve written songs in the past in which half a dozen instruments are all playing different melodies in the pentatonic scale. All I did was make sure that each instrument sounded good alone, and then loosed them against each other. Everything fit together perfectly because the harshest dissonance that any two pitches formed was a major second. This is a remarkably consonant scale.
The pentatonic scale is often used to evoke images of the Far East.
The minor pentatonic scale is simply a rotation of its relative major.
