So I gotta confess... I really didn't get into arpeggios until I got into Jazz. Now I use them in blues and rock and pretty much everything I do because they're what you use a lot when you think in terms of chords rather than keys.

The notes in an arpeggio spell out the notes of a chord in order so when there are many chord changes and you don't have the time or mental capacity to deal with keys or modes for each chord you can use arpeggio notes to get you through.

The more I study music the more arpeggios make sense and it seems many of the great 'uneducated players' use them all the time without knowing it - because they sound great!

From a listeners point of view, when you use arpeggios it sounds like you know what you're doing... so do ya? Punk ;)