PRIVMSG <nick1|channel1[,nick2|channel2...]> :message

PRIVMSG will send a standard message to the
user or channel specified.

PRIVMSG supports the following prefixes for sending
messages to specific clients in a channel:

@ - channel operators only
% - channel operators and half-ops
+ - operators, half-ops, and voiced users

Two other targets are permitted:

$$servermask - Send a message to a server or set of
               servers
$#hostmask   - Send a message to users matching the
               hostmask specified.

These two are operator only.

The nick can be extended to fit into the following
syntax:

username[%hostname]@servername

This syntax (without the hostname) is used to securely
send a message to a service or a bot.