ERC is a modular, extensible Emacs Internet relay chat client. It is available as part of GNU Emacs. You can use it to connect to irc.freenode.net (for example) chat server using:

;; .emacs
(load "/path/to/secrets.el")

;; erc
(defun erc-freenode-connect ()
  (interactive)
  (erc :server "irc.freenode.net" :port 6667 :full-name "<Firstname Lastname>" 
   :nick "<your-nickname-here>")
  (require 'erc)
  (require 'erc-match)
  (setq erc-keywords '("<your-nickname-here>"))
  (setq erc-current-nick-highlight-type 'nick)
  (setq erc-track-exclude-types '("JOIN" "PART" "QUIT" "NICK" "MODE"))
  (setq erc-track-use-faces t)
  (setq erc-track-faces-priority-list
	'(erc-current-nick-face erc-keyword-face))
  (setq erc-track-priority-faces-only 'all)
  (setq erc-input-line-position -2)
  (setq erc-echo-notices-in-minibuffer-flag t)
  (setq erc-autojoin-channels-alist 
	'(("freenode.net" "#fedora-india" "#fedora-devel" "##linux-india" 
            "#edev" "#fedora-arm" "#fedora-haskell" "#fudcon-planning" "#gcc"
  	    ))))

(defun nickname-freenode-after-connect (server nick)
  (when (and (string-match "freenode\\.net" server)
	     (boundp 'irc-freenode-nick-passwd))
    (erc-message "PRIVMSG" (concat "NickServ identify " irc-freenode-nick-passwd))))
(add-hook 'erc-after-connect 'nickname-freenode-after-connect)

The secrets.el file loads your encrypted files that contain passwords:

;; secrets.el
(load-library "~/pass.el.gpg")

A sample pass.el.gpg file:

;; pass.el.gpg
(set 'irc-freenode-nick-passwd "your-password")

The first time you load the above, you will be prompted to create a password for the encryption. Remember it. Whenever you start Emacs thereafter, or when you try to modify the .gpg files, you will be prompted for the password. To initiate connection to irc.freenode.net within Emacs, you can use:

M-x erc-freenode-connect

It should connect to the server, join you to the channels, and identify yourself to NickServ! Each channel is a buffer, and thus Emacs buffer commands work. Whenever someone sends you a message using your nick, you will get a notification in the Emacs status bar. For more ERC commands and options, please refer the ERC user manual.