Chatting:
There are multiple chat channels in this game.  Upon logging in they will all be open, but you can choose to only listen to 1 by clicking just below the scroll arrows for the chat menu.  You can speak in specific chat channels by clicking to the left of the chat entry space near the bottom left of the screen.

Tk = Normal talking.  People who are near you can hear you.
Ws = Whisper.  Between the chat channel button and the chat entry space you can input the name of a character and chat with that character no matter what map you’re on.

Fr = Friend.  Talk to anyone on your friend’s list, regardless of where you are.

Tm = Team.  If you have joined a Team you can talk to just your team members.

Lg = Legion.  If you have joined a Legion you can talk to just you legion members.