A live webcast means taking the media and broadcasting it in real time over the Internet. Live media streams are generally provided by a means called true streaming. Live streaming sends the information straight to the computer or device without saving the file to a hard disk.
Basically, audio or video content from an audio/visual system (such as a video camera) is transferred to streaming software running on the host's computer. The content is encoded (compressed and digitized), and then sent to a specialized server known as a content delivery network (CDN). The CDN distributes and delivers the media onto the Internet - either as a live broadcast, or as "on demand" for later access. Potential end-users are able to view or listen to a webcast because a media publishing program on their computers (such as RealPlayer or Windows Media Player).This program decodes or converts the data stream from the CDN.