Web conferencing combines video and audio conferencing over the internet with real-time media sharing and presentation applications. In a typical web conferencing scenario one user acts as the host of the conference, presenting a document or web page to other users that are connected via a desktop application or browser plugin and can follow the presenter's narration, see and comment the presented document.
For certain uses cases in real-time collaboration, web conferencing is a powerful alternative to chat rooms and file sharing. The advantage here is the richer media experience.