The word pentatonic comes from the Greek pente meaning five, and tonic meaning tone. The scale is made up of five tones within an octave. The two main forms of the pentatonic scale are major and minor. The major pentatonic scale uses the 1st, 2nd, 3rd, 5th and 6th notes of the major scale.
In the video below Bobby McFerrin demonstrates the power of the (major) pentatonic scale, using audience participation, at the event “Notes & Neurons: In Search of the Common Chorus”, from the 2009 World Science Festival, June 12, 2009.