[widdershins]

If you play a chord into an arpeggiator, it... well, it arpeggiates it. In other words, it plays each note of the chord individually in a particular rhythm (e.g. 16th notes) in a particular pattern (e.g. up/down, up, random). Very, very common in electronic music.

[mitchty]

Cool I had no idea, I'm about as musical as... umm, yeah i've got no analogue.

Does it get scaled in specific patterns or is random ok?

[eropple]

Patterns, random, fast, short, whatever. Most packaged arpeggiators have all sorts of knobs to twist.