socket.io - socket.emit, socket.on, socket.send

Base from the official site of socket.io http://socket.io/#how-to-use, I cant find any terminologies. What are the difference between socket.emit , socket.on , and socket.end ? Can't find articles which differentiate these things. Im currently developing a real-time application.

socket.emit - This method responsible for sending messages. socket.on - This method responsible for listening for incoming messages. socket.end - This is the first time i'm hearing about this method. I don't really sure that this method exists.