As you advance in your guitar studies you will surely come across the study of arpeggios. For many new guitarists arpeggios can be confusing, but they don't need to be.
One reason they cause some confusion is that - even though arpeggios are played as a series of single notes, similar to scales - they are not the same as scales.
The first step is to clear up the differences between arpeggios and scales.
Scales
A series of notes played on the guitar that fit sonically within a particular key signature are known as a "scale".
Arpeggios
A series of notes played on the guitar that consists of the notes within a particular chord.
The next step in understanding the difference between arpeggios and scales is to look at how they are used when soloing.
How Scales are Used
The notes within a particular scale can be played over all, or most, of the chords that are in the chord progression of the song you are playing.
For example - The notes of the C major scale consist of the following 8 notes:
C D E F G A B C
Note that the first and last notes of the scale are the "root" notes of the scale.
You can use these eight notes when soloing over all, or most, of the chords in a progression that is in the key of C major.
How Arpeggios are Used
For the most part arpeggios only consist of four notes, and they are usually the four notes that the chord is built from.
In essence, what you are doing with an arpeggio is playing the chord, but only playing it one note at a time.
For example - Staying with the above discussion, a C major arpeggio would consist of the following four notes:
C E G C
Note that C E & G are the first, third and fifth notes of the C major scale and that these three intervals are what comprise a major triad, which is where the major chord comes from.
You typically would use these for notes only when soloing over a C major chord - as opposed to the notes in the C major scale, which might be used to solo over all the chords in the progression.
In Summary
When using scales in soloing you can typically play those notes throughout all or most of the progression in a particular key.
When using an arpeggio you would normally play those notes over the chord of which the arpeggio is built.
This requires a more chordal approach to your soloing. Technically you could play a separate arpeggio over each chord in a progression. In fact, this is what many jazz guitarists actually do.
Arpeggios are also a great tool to use when there is one chord in a progression that doesn't "fit" or work well when using the notes of the scale in that particular key. When you encounter the chord that doesn't fit with the scale notes, simply play the notes in the arpeggio of that chord.
Now that you know the difference between arpeggios and scales, it's time to get to work and start making use of that knowledge in your solos!
