Podcasting is a term used to describe a collection of technologies for automatically distributing audio and video programs over the internet via a publish and subscribe model. It differs from earlier online collections of audio or video material because it is automatic, usually through RSS feeds. Podcasting enables independent producers to create self-published, syndicated "radio shows," and gives broadcast radio or television programs a new distribution method.
In the podcasting model, the publisher publishes a list of programs in a special format, known as a "feed", on the web. A user who wants to see or hear the podcast subscribes to the feed in special "podcatching" software (a type of aggregator), which periodically checks the feed and automatically downloads new programs as they become available. Typically, the podcatching software also transfers the program to a desktop or portable media player.
Any digital audio player or computer with audio-playing software can play podcasts. From the earliest RSS-enclosure tests in 2000-2001, feeds have been used to deliver video files as well as audio. By 2005 some aggregators and mobile devices could receive and play video, but the "podcast" name remained most associated with audio.
Name
"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 player, and no broadcasting is required.
Aware of that misleading association from the beginning, some writers have suggested alternative names or reinterpretations of the letters "p-o-d". One alternative is "blogcasting", which implies content based on, or similar in format to, blogs. Another is "audioblogging." Yet another is "rsscasting". In 2005, the term POD has been described as "Personal On Demand" radio.
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History
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Initial development
By 2003, web radio had existed for a decade, digital audio players had been on the market for several years, blogs and broadcasters frequently published MP3 audio online, and RSS file formats were widely used for summarizing or syndicating Web content. In 2001, UserLand founder and RSS evangelist Dave Winer responded to requests from customers Adam Curry[1] and Tristan Louis[2] for a way to deliver video or audio with their RSS feeds. Winer added a specific enclosure element to what was then his company's RSS specification, then to Radio Userland, a blogging system incorporating both a feed-generator and aggregator.[3] (Ironically, the rival RDF Site Summary syndication format already supported media resources implicitly, although applications rarely took advantage of the feature.)
In June 2003, Stephen Downes demonstrated aggregation and syndication of audio files using RSS in his Ed Radio application [4]. Ed Radio scanned RSS feeds for MP3 files, collected them into a single feed, and made the result available as SMIL or WebJay audio feeds.
In September 2003, Winer created an RSS-with-enclosures feed for his Harvard Berkman Center colleague Christopher Lydon, a former newspaper and television journalist and public radio radio talk show host [5]. For several months Lydon had been linking full-length MP3 interviews to his Berkman weblog, which focused on blogging and coverage of the 2004 U.S. presidential campaigns. At the first Harvard BloggerCon conference, October 4-October 5, 2003, Kevin Marks demonstrated a script to download RSS enclosures to iTunes and synchronise them onto an iPod[6], something Adam Curry had been doing with Radio Userland and Applescript. Listening to Lydon's interviews on an iPod helped inspire Adam Curry to create a feed he called "syncpod," which was used for testing by Marks, Werner Vogels and other developers at the conference, some of whom became involved in open source iPodder development projects.
Curry's and Winer's podcasts, including several months of collaboration they called "Trade Secrets," spread interest in podcasting among other widely-read bloggers. Amateur blogs and open source developers continued as important factors in the popularization of podcasting before and after professional broadcasters and entrepreneurs with business plans adopted the form.
Possibly the first use of the term podcasting was as a synonym for audioblogging or weblog-based amateur radio in an article by Ben Hammersley in The Guardian on February 12, 2004 [7]. In September of that year, Dannie Gregoire used the term to describe the automatic download and synchronization idea that Curry had developed [8]. Gregoire had also registered multiple domain names associated with podcasting. That usage was discovered and reported on by Curry and Dave Slusher of the Evil Genius Chronicles website.
By October 2004, detailed how-to podcast articles[9] had begun to appear online. In November 2004, liberated syndication libsyn launched what was apparently the first Podcast Service Provider, providing storage, bandwidth, and RSS creation tools.
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Podcast! 
Linear Mode
