RSS / TWITTER
The term "podcast" is a portmanteau of the words "Play-On-Demand"(POD) and "broadcast". Podcasting is a way of distributing and downloading Internet audio archives so that the user can listen to them on their MP3 player or computer at their leisure. Through a syndicated system (RSS), users can subscribe to this free service, which offers quick and automatic downloads as the podcasts become available. The objective is to be able to listen to the preferred audio broadcasts without having to constantly visit the website that provides them. You will need an specific software to subscribe podcast such as: Juice, Doppler Radio, iPodderX and Liferea (Linux Feed Reader).
More information at Wikipedia.