From Wikipedia, the free encyclopedia.
Internet Relay Chat (IRC) is a form of instant communication over the Internet. It is mainly designed for group (many-to-many) communication in discussion forums called channels, but also allows one-to-one communication.
IRC is an open protocol that uses TCP and optionally SSL. An IRC server can connect to other IRC servers to expand the IRC network. Users access IRC networks by connecting a client to a server. There are many client and server implementations. Most IRC servers do not require users to log in, but a user will have to set a nickname before being connected.
IRC is a plaintext protocol, which means that it is fully possible (though quite inconvenient) to use IRC via a basic byte-stream client such as netcat or telnet. However, the protocol only uses a slightly modified version of ASCII, and does not originally provide any support for non-ASCII characters in text, with the result that many different, incompatible character encodings (such as ISO 8859-1 and UTF-8) are used.
Because most IRC implementations use an acyclic graph as their connection model, there is no redundancy, and outage of a server or a link can cause a netsplit.