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.
Web conferencing may be used as an umbrella term for various types of online collaborative services including web seminars ("webinars"), webcasts, and peer-level web meetings. It may also be used in a more narrow sense to refer only to the peer-level web meeting context, in an attempt to disambiguate it from the other types of collaborative sessions. Terminology related to these technologies is inexact, and no generally agreed upon source or standards organization exists to provide an established usage reference.
Real-time text chat facilities such as IRC appeared in the late 1980s. Web-based chat and instant messaging software appeared in the mid-1990s. The PLATO computer learning system allowed students to collaborate on networked computers to accomplish learning tasks as early as the 1960s, but the early networking was not accomplished via the World Wide Web and PLATO's collaborative goals were not consistent with the presenter-audience dynamic typical of web conferencing systems. PLATO II, in 1961, featured two users at once.
In 1992, InSoft Inc. launched Communique, a software-based Unix teleconferencing product for workstations that enabled video/audio/data conferencing. Communique supported as many as 10 users, and included revolutionary features such as application sharing, audio controls, text, graphics, and whiteboarding which allowed networked users to share and manipulate graphic objects and files using simple paint tools.
In May 1995, PictureTel announced LiveShare Plus as a general-use data collaboration product for Windows-based personal computers. The software allowed application sharing, user-granted control of a remote PC, shared whiteboard markup, file transfer, and text messaging. List price was given as $249 per computer. PictureTel referenced an agreement with Microsoft in its announcement press release, and a May 26, 1995 memo from Bill Gates to Microsoft executive staff and direct reports said "Our PictureTel screen sharing client allowing Window sharing should work easily across the Internet."
Web conferencing software is invoked by all participants in a web meeting. Some technologies include software and functionality that differs for presenters and attendees. Software may run as a web browser application (often relying on Adobe Flash, Java, or WebRTC to provide the operational platform). Other web conferencing technologies require download and installation of software on each participant's computer, which is invoked as a local application. Many web conferencing vendors provide the central connectivity and provisioning of meeting "ports" or "seats" as a hosted web service, while others allow the web conference host to install and run the software on its own local servers. Another installation option from certain vendors allows for use of a proprietary computer appliance that is installed at the hosting company's physical location.