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.
In 1996, PlaceWare was founded as a spinoff from Xerox PARC. In November of that year, PlaceWare Auditorium was described in a public talk at Stanford University as allowing "one or more people to give an interactive, online, multimedia presentation via the Web to hundreds or thousands of simultaneous attendees; the presentation can include slides (made in PowerPoint or any GIF-image editor), live annotation on the slide images, real-time polls of the audience, live audio from the presenter and those asking questions, private text and audio conversations in the auditorium's "rows", and other features." PlaceWare Auditorium was formally announced in March 1997 at a price of $150 per simultaneous user.
A webinar is a live, web-based video conference that uses the internet to connect the individual (or multiple individuals) hosting the webinar to an audience of viewers and listeners from all over the world. Hosts can show themselves speaking, switch to their computer screens for slideshows or demonstrations, and even invite guests from other locations to co-host the webinar with them.