The music of Western Europe developed separately from that of other nations throughout history. The music theory and structure that we study in my courses (and in most North American and West European schools) comes from this Western European history. Western tonal music is based off of 7 pitches within a given diatonic key. Our key system can be based on either a major or minor tonality.
The Middle East, Eastern Europe, Asia, Africa, Australia and even Native Americans all have their own musical history and structure that differs in many ways from Western Music. Some of these areas (particularly the Middle East and Asia) developed a formal music theory which we classify as Eastern music. This difference creates a split in music theory when referring to either Eastern or Western music.
There are two main types of pentatonic scales: hemitonic and anhemitonic. Hemitonic scales contain one or more semitones. Anhemitonic scales contain no semitones. Anhemitonic scales are the type of pentatonic scales that occur in Western music, since they relate best to our diatonic keys. They will be the focus of the rest of our discussion.
The two main types of anhemitonic pentatonic scales that we identify in Western music are major and minor pentatonic. The major pentatonic scale is composed of the 1st, 2nd, 3rd, 5th and 6th scale degrees of a major diatonic scale. This scale is useful for the implementation of simple improvisation techniques because it does not contain the 7th scale degree. This makes it a good scale for use improvising over both major 7th and dominant 7th chords. In addition, the scale does not contain the 4th scale degree which is considered an "avoid" tone in jazz improvisation.
In this Learning Music With Ray video I discuss the definition and composition of pentatonic scales. I cover a brief history of the difference between Western and Eastern music and the use of pentatonic scales within these two frameworks. I then go into a more detailed discussion on the pentatonic scales that are most common to Western music. Finally I cover tips on how to determine the pitches of these pentatonic scales.