Right of way rules determine who has the "right of way" and who should "yield, or get out of the way" when passing.
A kiter on a starboard tack (right hand and shoulder forwards) has right of way.
A kiter on a port tack (left hand and shoulder forwards) must yield right of way (get out the way, pass downwind).
For two kiters on the same tack, the kiteboarder upwind must give way to the kitesurfer downwind.
While passing in opposite directions:
Riders close to shore or negotiating broken water are more at risk, so they have the right of way
Kiters riding on a wave have right of way over other riders, except for outgoing riders as above.