Real-time text in the context of Synchronous conferencing

Online chat is any direct text-, audio- or video-based (webcams), one-on-one or one-to-many (group) chat (formally also known as synchronous conferencing), using tools such as instant messengers, Internet Relay Chat (IRC), talkers and possibly MUDs or other online games. 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. Online chat may address point-to-point communications as well as multicast communications from one sender to multiple receivers and voice and video chat, or may be a feature of a web conferencing service.

Online chat in a narrower sense is any kind of communication over the Internet that offers a real-time transmission of text messages from sender to receiver. 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. The expression online chat comes from the word chat which means "informal conversation".

Web conferencing is used as an umbrella term for various types of online conferencing and collaborative services including webinars (web seminars), webcasts, and web meetings. Sometimes it may be used also in the more narrow sense of the peer-level web meeting context, in an attempt to disambiguate it from the other types known as collaborative sessions.

In general, web conferencing is made possible by Internet technologies, particularly on TCP/IP connections. Services may allow real-time point-to-point communications as well as multicast communications from one sender to many receivers. It offers data streams of text-based messages, voice and video chat to be shared simultaneously, across geographically dispersed locations. Applications for web conferencing include meetings, training events, lectures, or presentations from a web-connected computer to other web-connected computers.