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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. 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. ==Installation and Operation== 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 Webster 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. Depending on the technology being used, participants may speak and listen to audio over standard telephone lines or via computer microphones and speakers. Some products allow for use of a webcam to display participants, while others may require their own proprietary encoding or externally-provided encoding of a video feed (for example, from a professional video camera connected via an IEEE 1394 interface) that is displayed in the session. Vendor-hosted web conferencing is usually licensed as a service based on one of three pricing models: a fixed cost per user per minute, a monthly or annual flat fee allowing unlimited use with a fixed maximum capacity per session, or a sliding rate fee based on the number of allowed meeting hosts and per-session participants (number of "seats"). Presentation of visual materials most often is accomplished through one of two primary methodologies. The web conferencing software may show participants an image of the presenter's computer screen (or desktop). Again, depending upon the product, the software may show the entire visible desktop area or may allow selection of a physical area or application running on the presenter's computer. The second method relies on an upload and conversion process (most commonly consisting of Microsoft PowerPoint files, other Microsoft Office electronic documents, or Adobe PDF documents). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Web conferencing」の詳細全文を読む スポンサード リンク
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