ERC is a powerful, modular, and extensible IRC client for Emacs.
For more information, visit the ERC page at
<https://www.gnu.org/software/emacs/erc.html>.

Configuration:

Use M-x customize-group RET erc RET to get an overview
of all the variables you can tweak.

Usage:

To connect to an IRC server, do

M-x erc RET

or

M-x erc-tls RET

to connect over TLS (encrypted).  Once you are connected to a
server, you can use C-h m or have a look at the ERC menu.