If I walk into a zone having completed X requirement, and my buddy hasn't done that yet, maybe I see red trees, and he sees green. No harm, no foul. What if I see an enemy though, and he doesn't? What if the enemy attacks me? Does he see me standing there, swinging my weapon at nothing, looking like a fool? Or do I suddenly disappear before his very eyes, into my own little version of the world?

I mentioned Booty Bay as a good example because I was doing a lot of stuff there at the conclusion of a long chain. Fighting guys, swinging about on ropes, etc. Was I invisible to the rest of the players? Even though I was in a city? Could I see them (I didn't think to look)? Did I pass through some mini instance portal?

Anyway, I can look this stuff up at some point, you don't have to explain it to me. Just confused on how it all works at the moment. Thanks for the term "phasing," though. That should be something I can successfully Google.