channel
channel -invite
channel <channel list>
channel <channel list> <key list>

Channels are the most important part of IRC. A “channel” is a place where one or more people can congregate and talk to each other. Each channel has a name, and there are an almost limitless number of channels available. Channels are shared amongst all of the servers of a network. Each network has a different set of channels than every other network.

You can join a channel with the JOIN (or CHANNEL) command. The JOIN command takes one argument, which is the name of the channel that you want to join. If you do not know the name of a channel, then you can try joining the #irchelp channel to get started.

Channels “exist” as long as there is one person in them. When the last person leaves a channel, the channel “goes away”. When the first person join a channel, the channel is “created”. The creator of a channel becomes the channel operator. Whenever you join a channel, you become a “member” of that channel. Channel operator privilege can be shared amongst all of the members of the channel.

Network channel names always begin with the # character. Channels that exist only on your server always begin with the & character. Some networks have channels that do not allow the MODE command and those channels always begin with the + character.

Channel names can be up to 200 characters in length (though most channel names are 1 to 10 characters long), and can contain any character except SPACE, BELL, NUL, CR, LF, and the comma.

Some networks permit you to restrict your channel to only users from a certain host pattern. On those networks, you append to the channel name the colon character (':') followed by a hostmask. Only users with hostnames that match the hostmask will be permitted to join your channel.

You may join more than one channel at a time by separating the list of channels you want to join with commas.

If a channel requires a “key” to enter, provide the channel key as the second argument to the JOIN command. Try to avoid joining more than one channel at a time if any of the channels have a key, as not every server can handle this correctly. Joining each channel with a key separately will work the best.

You cannot always join every channel all of the time. A channel's mode may restrict you from joining it. If the +k mode (key) is set, then you must use the key (password) to join. If the +i mode (invite-only) is set, then you must be INVITEd by a channel operator to join. If the +l mode (limited membership) is set, and the number of members in the channel has reached the limit, then you cannot join. If a +b mode (ban) has been set for your hostmask, then you cannot join. On some networks, if a +e mode (exception to ban) has been set for your hostmask, you can join even if there is a +b mode for your hostmask. Please read the MODE help file for more detailed information about channel modes.

If you do not use any arguments, the JOIN command will show you a list of all of the channels you have joined and the information that is known about those channels.

If you do use arguments, the first argument must be a comma separated list of channels you want to join. If any of your channels require a key (the channel mode +k is set) then you must specify that key as the second argument. Care should be taken when joining multiple channels with keys at the same time because not all networks do it the same way.

If you specify one channel, then that channel will be made the current channel in the window you do the /JOIN in (as if you did a /WINDOW CHANNEL). CAUTION! If you specify more than one channel, none of them will be made the current channel.

To join channel #irchelp (or create it if it does not exist):

    /channel #irchelp

To join channel #blah that has the key “foobar”:

    /channel #blah foobar

To join more than one channel at once:

    /channel #foo,#bar,&blah

To join a channel that only German users may join: (on some networks)

    /channel #blah:*.de

To join channel #blah if you have been invited to it (either will work, although the first is better, since channel names may contain characters that your terminal can't display):

    /channel -invite
    /channel #blah

CHANNEL is just a front end for WINDOW REJOIN. The JOIN command is by custom a scripted alias.