If you can join IRC channels and send messages, you know enough to chat as long as you want without learning any more about IRC. You'll see other people do some interesting things, though, such as taking "actions." By learning a handful of the many available IRC commands, you can do those same things. The following commands, and many others, are explained in short form in IRC Command Quick Reference.
Note:  The following instructions assume that you've connected to an IRC server, joined a chat channel and clicked in the outgoing message pane at the bottom of a channel window.
To change your nickname, type /NICK followed by a space and a new nickname. Press ENTER. Don't include quotation marks or your old nickname. Your nickname changes in all chat windows you have open.
You can display an "action" instead of just sending a comment. The message pane displays a narrative description of an action, instead of just a message. Usually, an action is displayed in a special color, or in some other way that sets it off from most text. Suppose your nickname is Newbie and you want to indicate you're confused. You could display the action "Newbie shrugs and looks clueless."
To display an action:
If /ME doesn't work, instead use /ACTION, like this:
Instead of clicking a Join button or menu item, you can simply type /JOIN followed by a space, and a channel name. Press ENTER. The channel name must begin with the pound "#" sign. If you type in a channel name that doesn't already exist, a new channel is created. A windows appears for the channel. At first, you're the only person on that channel, but others are likely to join you.
If you're going to do something else for awhile but you don't want to quit being in a channel, you can leave an "away" message. This is the electronic equivalent of tacking up an "Out to Lunch" or "Gone Fishing" sign. When other people inquire about you they see your "away" message.
To leave an "away" message:
To stop displaying an "away" message:
You can learn some basic information about the people behind the nicknames you see on chat channels. Typically, this information includes a person's e-mail address and real name, or whatever they typed in those text boxes. It also shows their nickname, a list of the channels they're on, the IRC server they're connected to, and any special message they left in case someone checked their information (see Leaving an Away Message). Other people can learn about you by using this command and viewing the information that you have entered into your own IRC client software.
To learn about someone on a chat channel:
You can invite someone else on an IRC server to join a channel you're using. Suppose your nickname is Newbie and you're on a channel called #Newbies. A person invited by you would see a message something like this: "Newbie invites you to #Newbies."
To invite someone to join a channel you're using:
To start a private chat:
You can set your IRC client so it doesn't display any messages sent by particular nicknames. This is useful if someone is harassing you, or if people are flooding channels with pointless text that causes your window to scroll rapidly.
To ignore someone:
To stop ignoring someone: