A trademark for the term WEBinar (first three letters capitalized) was registered in 1998 by Eric R. Korb (Serial Number 75478683, USPTO) and was reassigned to InterCall. The trademark registration was cancelled in 2007. Learn.com filed a claim for the term "webinar" without regard to font or style in 2006 (Serial Number 78952304, USPTO). That trademark claim was abandoned in 2007 and no subsequent filing has been made.
The term "webcast" derives from its original similarity to a radio or television broadcast. Early usage referred purely to transmission and consumption of streaming audio and video via the World Wide Web. Over time, webcast software vendors have added many of the same functional capabilities found in webinar software, blurring the distinction between the two terms. Webcasts are now likely to allow audience response to polls, text communication with presenters or other audience members, and other two-way communications that complement the consumption of the streamed audio/video content.
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.
Using Webinar software participants can share audio, documents and applications with webinar attendees. This is useful when the webinar host is conducting a lecture or information session. While the presenter is speaking they can share desktop applications and documents. Today, many webinar services offer live streaming options or the ability to record your webinar and publish to YouTube and other service later.