The word pentatonic is referring to a particular type of scale. Pent means five so a pentatonic scale has five notes in it. There are mainly two types of pentatonic scales which are the Major Pentatonic and the Minor Pentatonic Scales. In my opinion pentatonic scales are over played by musicians in their solos. However if the musician uses it skillfully it can sound a whole lot more advanced than just a simple pentatonic scale. They are easy to play and if you really learn how to use the pentatonic scales they can really be a powerful tool in your musical arsenal.

In the key of C Major. The C major scale consists of notes C – D – E – F – G – A – B – C

C = #1 D =#2,
E= #3 F =#4
G =#5 A =#6
B =#7 C =#8

Within a major scale a Major Pentatonic Scale consists of the numbers 1, 2 , 3, 5, and 6
Therefore in the key of C Major the C Major Pentatonic Scale would be C, D ,E, G, and A

The Minor Pentatonic Scale consists of the number 1, b3, 4, 5, b7
Therefore in the key of C Major the C Minor Pentatonic Scale would be C, Eb, F, G, Bb

Minor Pentatonic Scales work well over minor chords or if you are trying to create a bluesy sound. Major Pentatonic work well over major chords.