Changing servers questionFollow

Can you change servers freely? As in can I take my chracter from one realm to another without a problem or am I completely locked into a server. My real worry is that I will join a PvP server and as the PvP developed the law of unforseen consequences will take affect and the game would be rendered unplayable. I dont think this will happen but I am just wonderring if you had a bad PvP server experience can you then go to a non PvP server if you want to