This illustration shows  two browser windows. 
Both windows display the chat interface.
The same sent messages are displayed on both windows. 
A  Hello message was just sent from John's window.

Messages are:
John: Hello Ed, How are you
John: Joined the chat
Ed: Hi!
Ed: Joined the chat

The text field in Ed’s window shows the following new message, which hasn’t been sent yet:
Great. Thanks!