There are a group of five note scales known collectively as pentatonic scales. Intervals in a traditional pentatonic scale are normally limited to whole steps and minor thirds. Many performers use these relatively simple scales to good effect, including McCoy Tyner and Woody Shaw. The two basic pentatonic scales are the major pentatonic scale and the minor pentatonic scale. A C major pentatonic scale is “C, D, E, G, A”, and a C minor pentatonic scale “C, Eb, F, G, Bb”. Note that the C minor pentatonic scale is actually the fifth mode of an Eb major pentatonic scale. Other modes of the pentatonic scales are used as well, such as “C, D, F, G, Bb”, which is the second mode of the Bb major pentatonic scale. This scale can be called the suspended pentatonic scale, although this usage is by no means standard.
As their names imply, the major, minor, and suspended pentatonic scales can be used over major, minor, and suspended chords respectively. For instance, the C major pentatonic scale can be used over Cmaj7. Sometimes this chord is written C6 to imply more strongly that the major pentatonic scale is to be used. The C minor pentatonic scale can be used over Cm7. The C suspended pentatonic scale can be used over a C7sus chord.
Other five note scales are used occasionally as well. For instance, the scale “E, F, A, B, D” is the traditional Japanese “in sen scale”. It can be used as a substitute for the E phrygian mode (note it in fact defines the E phrygian chord) to impart an Asian flavor to the music. Useful variations of this scale include the second mode, “F, A, B, D, E”, which can be used over a Fmaj7#11 chord; the fourth mode, “B, D, E, F, A”, which can be used over a Bm7b5 chord; and the fifth mode, “D, E, F, A, B”, which can be used over a Dm6 chord.
Since there are relatively few notes in a pentatonic scale, one pentatonic scale can often be used over several different chords with no real avoid notes. For instance, the C major pentatonic scale “C, D, E, G, A” could be used over Cmaj7, C7, D7sus, Dm7, Em7b6, Fmaj7, G7sus, Gm7, or Am7.