Chat messages are generally short in order to enable other participants to respond quickly. Thereby, a feeling similar to a spoken conversation is created, which distinguishes chatting from other text-based online communication forms such as Internet forums and email.

Online chat may address point-to-point communications as well as multicast communications from one sender to many receivers and voice and video chat, or may be a feature of a web conferencing service.

Online chat in a less stringent definition may be primarily any direct text-based or video-based (webcams), one-on-one chat or one-to-many group chat (formally also known as synchronous conferencing), using tools such as instant messengers, Internet Relay Chat (IRC). The expression online chat comes from the word chat which means "informal conversation". Online chat includes web-based applications that allow communication –often directly addressed, but anonymous between users in a multi-user environment. Web conferencing is a more specific online service that is often sold as a service, hosted on a web server controlled by the vendor.

History

The first online chat system was called Talkomatic, created by Doug Brown and David R. Woolley in 1974 on the PLATO System at the University of Illinois. It offered several channels, each of which could accommodate up to five people, with messages appearing on all users' screens character-by-character as they were typed. Talkomatic was very popular among PLATO users into the mid-1980s.

The first dedicated online chat service that was widely available to the public was the CompuServe CB Simulator in 1980, created by CompuServe executive Alexander "Sandy" Trevor in Columbus, Ohio. Ancestors include network chat software such as UNIX "talk" used in the 1970s.

Chatiquette

The term chatiquette (chat etiquette) is a variation of netiquette (Internet etiquette) and describes basic rules of online communication. To avoid misunderstandings and to simplify the communication between users in a chat these conventions or guidelines have been created. Chatiquette varies from community to community, generally describing basic courtesy; it introduces new user into the community and the associated network culture. As an example, it is considered rude to write only in upper case, because it appears as if the user is shouting.

The word chatiquette has been used in connection with various chat systems (e.g. Internet Relay Chat) since 1995.

Despite being virtual, chat can spill into the outside world. There can also be a strong sense of online identity leading to impression of subculture.

Chats are valuable sources of various types of information, the automatic processing of which is the object of chat/text mining technologies.

Social criticism

Criticism of online chatting and text messaging include concern that they replace proper English with shorthand or with an almost completely new hybrid language.

Writing is changing as it takes on some of the functions and features of speech. Internet chat rooms and rapid real-time teleconferencing allow users to interact with whoever happens to coexist in cyberspace. These virtual interactions involve us in 'talking' more freely and more widely than ever before. With chatrooms replacing many face-to-face conversations it is necessary to be able to have quick conversation as if the person were present, so many people learn to type as quickly as they would normally speak. Critics are wary that this casual form of speech is being used so much that it will slowly take over common grammar; however, such a change has yet to be seen.

With the increasing population of online chatrooms there has been a massive growth of new words created or slang words, many of them documented on the website Urban Dictionary. Sven Birkerts wrote: "as new electronic modes of communication provoke similar anxieties amongst critics who express concern that young people are at risk, endangered by a rising tide of information over which the traditional controls of print media and the guardians of knowledge have no control on it".

In Guy Merchant's journal article Teenagers in Cyberspace: An Investigation of Language Use and Language Change in Internet Chatrooms; Merchant says "that teenagers and young people are in the leading the movement of change as they take advantage of the possibilities of digital technology, drastically changing the face of literacy in a variety of media through their uses of mobile phone text messages, e-mails, web-pages and on-line chatrooms. This new literacy develops skills that may well be important to the labor market but are currently viewed with suspicion in the media and by educationalists.

Software and protocols

The following are common chat programs

    Apple Messages

    AOL Instant Messenger (AIM)

    Camfrog

    Campfire

    Google Talk

    I2P-Messenger (anonymous, end-to-end encrypted im for the I2P network)

    Internet Relay Chat (IRC)

    Paltalk

    Skype

    Talk

    Talker

    TeamSpeak (TS)

    WebChat Broadcasting System (WBS)

    WhatsApp

    Windows Live Messenger

Web sites with browser-based chat services:

    eBuddy

    Facebook

    Google
    Tinychat