IRC - Stands for Internet Relay Chat is an internet based chat protocol. Main idea is to have users connect to a server network, where they can then send messages to each other through channels or direct chat. Today there's quite a few different networks, usually each with a main thematic. Stack Overflow got its own channel on the FreeNode network. You can read more about that on the full tag wiki page.
Overview
IRC is an internet chat protocol, first written in 1988. It bascially features IRC servers organized into networks, where an user can send message to other ones. The main feature is the channels that users can join, much like other chat rooms.
Network infrastructure and protocol
A network is generally made of several different servers, linked together through the same IRC protocol, where users and channels are common. Usually, just joining an empty channel will automatically create it, although this might not be the case everywhere. The IRC protocol also features moderators of different levels and channel options, although this has been found to be too weak for general use. Most IRC Networks now feature IRC Services, that enable someone to configure and protect channels in greater detail.
The IRC protocol only uses plaintext, as opposed to XMPP for example that uses XML style, and is therefore very simple to parse and use. Because of the lack of security of this approach, it's now usually used along a SSL connection. A typical IRC query is of the form: :origin KEYWORD contents - with the origin and contents sections being optional : a query could be as much as "LIST" to get a list of current network channels.
The server connection process is also very simple: the user only has to send out information about desired nickname, username, and displayed real name, before being able to use the network. Because of that, there has been quite a few implementation of IRC Bots and scripting platforms for various uses (EG. Eggdrop, Supybot, or simply home-made applications)
One of the big loopholes in the IRC protocol as described by RFC1459 is that it does not specify the use of character encoding past the 7-bit ASCII representation. Channels and users have been known to mostly use either utf-8 or latin-1 (iso8856-1). There's no shortage of problems made by bad software utf-8 parsers, to the extent of being able to crash people's client at will.
Stack Overflow IRC channel
Stack Overflow has an IRC channel on the FreeNode network (irc.freenode.net), #stackoverflow You could join it either by inputing above info in an IRC client, using This kind of browser link, or using a JS Web Applet such as FreeNode's QIRC. FreeNode is also the home of hundreds of community projects, especially open source ones.
More information
Detailed informations about the IRC protocol can be found into the IETF related RFCs, the initial one being RFC1459. Additions were later made, although some of these remain un-supported to this date.
Some popular IRC clients include:
- mIRC for Windows (see related questions)
- XChat, GTK Cross platform open source client
- Colloquy a popular free IRC client for Mac OS X
- irssi, a linux text based client (see related questions)
- The Lounge, a web-based open source client (see related questions)
Many other applications such as GNOME's Empathy, or Pidgin, also come with builtin IRC support.
