High Quality Content by WIKIPEDIA articles! A webcast is a media file distributed over the Internet using streaming media technology to distribute a single content source to many simultaneous listeners/viewers. A Webcast may either be distributed live or on demand. ESsentially, webcasting is ?broadcasting? over the Internet. THe largest "webcasters" include existing radio and TV stations, who "simulcast" their output, as well as a multitude of Internet only "stations". THe term webcasting usually refers to non-interactive linear streams or events.