Global chat
A server-wide chat next to alliance chat.
Stock Travian
Alliance chat is the only in-game public channel. Cross-alliance talk is IGMs and the forum.
Travikas
Everyone on the world shares one public channel. The last few dozen lines stay on screen. You can send a new line every three seconds. Admins can delete lines.
Rules of the room
English, no linking battle reports without both sides agreeing, no real-life threats. The game rules apply to chat the same as to village names.
Chat while you wait
When a window is closed you can still talk from the waiting page. That is the coordination channel for who is covering the next hit.