The word "podcasting" is a portmanteau that combines the words "broadcasting" and "iPod." The term can be misleading since neither podcasting nor listening to podcasts requires an iPod or any portable music player. For that reason, various writers have suggested reinterpreting the letters POD to create "backronyms" such as "Personal On-Demand." The term "Radio Me" was coined by Peter Day of the BBC for the same reason.
Podcasting is distinct from other types of online media delivery because of its subscription model, which uses the RSS 2.0 XML (or RDF XML) format to deliver an enclosed file. Podcasting enables independent producers to create self-published, syndicated "radio shows," and gives broadcast radio programs a new distribution method. Listeners may subscribe to feeds using "podcatching" software (a type of aggregator), which periodically checks for and downloads new content automatically. Some podcatching software is also able to synchronize (copy) podcasts to portable music players. Any digital audio player or computer with audio-playing software can play podcasts. The same technique can deliver video files, and by 2005 some aggregators could play video as well as audio.
