Emacs allows you to open multiple files at once, or open irc in emacs while editing, which is very helpful. You can open a new one using C-x 3
(split-window-right) or C-x 2
You can also use C-x 1
(delete-other-windows), which does exactly as it says it does, and deletes the other windows.
You can also use C-x 4 f to open a file in the other window. It calls the function