Teleporting to Players

Want to visit a friend? You do not need coordinates — just send a teleport request. The other player has to accept, so nobody can teleport to you uninvited.
Commands
/tpa <player> — ask to teleport to that player
/tpahere <player> — ask that player to teleport to you
/tpaccept — accept a request sent to you
/tpdeny — decline a request sent to you
When you send a request, the other player sees a message and can 
/tpaccept or 
/tpdeny. Requests time out after a short while if there is no answer.
Etiquette: 
/tpahere pulls someone away from whatever they were doing, so use it sparingly — 
/tpa to go to them is usually the polite choice.