Webcast is a media file distribution over the Internet using streaming media technology. It may be live or recorded. Simply the webcast is broadcasting over the Internet but in books you may read this definition - "transmission of linear audio or video content over the Internet". The largest “webcasters” include many radios and TV’s and stream their content over the Internet so many listeners/viewers can watch or listen their favorite shows for free. Webcast is used extensively in commercial and business sector too. Many companies use webcast for investor relations presentations, E-learning or for related communication activities.
The webcast technology is much affordable than the live multicast, so many free radios use it for online channels often produced by citizens in their home or garage but they cover many interesting topics. Interesting and cheap/accessible technology!!!