Podcast

Podcasting is the distribution of audio files, such as radio programmes, over the internet using RSS syndication for listening on mobile devices and personal computers. A podcast is a web feed of audio or video files placed on the Internet for anyone to subscribe to, and also the content of that feed. Podcasters' websites also may offer direct download of their files, but the subscription feed of automatically delivered new content is what distinguishes a podcast from a simple download or real-time streaming (see below).

While the name was primarily associated with audio subscriptions in 2004, the RSS enclosure syndication technique had been used with video files since 2001, before portable video players were widely available. In fact, any file with a URL, including still images and text, can be delivered as an enclosure.

Use of "podcast" to describe both audio and video feeds seemed natural to some users, while others preferred to reserve the word for audio and coin new terms for video subscriptions. Other "pod-" derived neologisms include "podcasters" for individuals or organizations offering feeds, and "podcatchers" for special RSS aggregators with the ability to transfer the files to media player software or hardware.

Podcasting's essence is about creating content (audio or video) for an audience that wants to listen when they want, where they want, and how they want.

Podcasting versus broadcasting and streaming

Subscribing to podcasts allows a user to collect programs from a variety of sources for listening or viewing offline at whatever time and place is convenient. In contrast, traditional broadcasting provides only one source at a time, and the time is broadcaster-specified. While podcasts are gaining ground on personal sites and blogs, they're not yet widespread. One easy way to find podcasts is to use the Podcast Directory in iTunes; these automatically-updated podcasts can then be easily synchronised to your iPod for offline listening.

"Streaming" files from the Internet can remove the specified-time restriction, but still offers only one source at a time, and requires the user to be connected to the Internet while playing the files. The ability to "aggregate" programs from multiple sources is a major part of the attraction of podcast-listening.

Unlike podcasts, streaming also can be used to broadcast live events over the Internet at the moment they occur.

Although streamed programs, like broadcast radio signals, can be recorded or captured by the receiver, their transient nature distinguishes them from podcast episodes, which arrive already in archived form. (This difference may make a podcast legally distinct from a webcast or streamed media file.)

Name

"Podcasting" is a portmanteau word coined in 2004 (see "History" below), that combined two words: "iPod" and "broadcasting."

Neither podcasting nor listening to podcasts requires an iPod or other portable player, and no over-the-air broadcasting is required. The name association came about simply because Apple Computer's iPod was the best-selling portable digital audio player when podcasting began and was used by early practitioners.

However, the use of the "pod" name in 2004 probably played a part in Apple's development of podcasting products and services in 2005, further linking the device and the activity in the news media.

The editors of the New Oxford American Dictionary declared "podcasting" the 2005 word of the year in December, defining the term as "a digital recording of a radio broadcast or similar program, made available on the Internet for downloading to a personal audio player".

From the beginning various writers suggested other names or alternative interpretations of the letters "P-O-D." Technology writer Doc Searls had proposed "Personal Option Digital" in September, 2004. The "Personal On Demand" interpretation was in international circulation as early as October 2004. In July 2005, Microsoft blogger Robert Scoble mentioned that interpretation while countering reports that his company was pushing the word "blogcasting" to avoid mentioning an Apple product. "Blogcasting" also implied content based on, or similar in format to, blogs, which was not always the case.

Another Apple rival in the portable audio and video market, Creative Technology, began using the "Personal On Demand" interpretation, while offering its own "Zencasts."

Other terms have been suggested, but had shortcomings -- "audioblogging," "audio magazines" and "webcasting" could describe other forms of media distribution, and "rsscasting," would be difficult to pronounce.

Podcasting as a medium was first associated with, but never limited to, audio data. As use of RSS enclosures for video spread in 2005, podcasting of video data was called, among other things, "video blogging", "video podcasting", "vlogging", "vodcasting", or "vidcasting".

Mechanics

The publish/subscribe model of podcasting is a version of push technology, in that the information provider chooses which files to offer in a feed and the subscriber chooses among available feed channels. While the user is not "pulling" individual files from the Web, there is a strong "pull" aspect in that the receiver is free to subscribe to (or unsubscribe from) a vast array of channels. Earlier Internet "push" services (e.g., PointCast) allowed a much more limited selection of content.

Podcasting is an automatic mechanism by which multimedia computer files are transferred from a server to a client which pulls down XML files containing the Internet addresses of the media files. In general, these files contain audio or video, but also could be images, text, PDF, or any file type.

A podcast is generally analogous to a recorded television or radio series.

The content provider begins by making a file (for example, an MP3 audio file) available on the Internet. This is usually done by posting the file on a publicly-available webserver; however, BitTorrent trackers also have been used, and it is not technically necessary that the file be publicly accessible. The only requirement is that the file be accessible through some known URI (a general-purpose Internet address). This file is often referred to as one episode of a podcast.

The content provider then acknowledges the existence of that file by referencing it in another file known as the feed. The feed is a machine-readable list of the URIs by which episodes of the show may be accessed. This list is usually published in RSS format, which provides other information, such as publish dates, titles, and accompanying text descriptions of the series and each of its episodes. The feed may contain entries for all episodes in the series, but is typically limited to a short list of the most recent episodes, as is the case with many news feeds.

The content provider posts the feed to a known location on a webserver. (Unlike the episode file itself, the feed is published to a webserver, usually not by other means.) The location at which the feed is posted is expected to be permanent. This location is known as the feed URI (or, perhaps more often, feed URL). The content provider makes this feed URI known to the intended audience.

A consumer enters this feed URI into a software program called a podcatcher or aggregator (the former term is specific to podcasting while the latter is general to all programs which collect news from feeds). This program retrieves and processes data from the feed URI.

A podcatcher is usually an always-on program which starts when the computer is started and runs in the background. It manages a set of feed URIs added by the user and downloads each at a specified interval, such as every two hours. If the feed data has substantively changed from when it was previously checked (or if the feed was just added to the podcatcher's list), the program determines the location of the most recent episode and automatically downloads it to the user's computer. Some podcatchers, such as iTunes, also automatically make the newly downloaded episodes available to a user's portable media player. (This is only the typical behavior of a podcatcher; some podcatchers behave—or can be set to behave—differently.)

The downloaded episodes can then be played, replayed, or archived as with any other computer file.

History

Initial development

What makes podcasting unique from other digital audio and video delivery is the use of syndication feed enclosures. The concept was proposed in a draft by Tristan Louis in October, 2000, and implemented in somewhat different form by Dave Winer, a software developer and an author of the RSS format. Winer had discussed the concept, also in October 2000, with Adam Curry, a user of his software, as well as having other customer requests for audioblogging features. He included the new functionality in RSS 0.92, by defining a new element called "enclosure", which would simply pass the address of a media file to the RSS aggregator. Winer demonstrated how the feature would work by enclosing a Grateful Dead song in his Scripting News weblog on January 11th, 2001.

For its first two years, the enclosure element had relatively few users. Winer's company incorporated the new feature in its weblogging product, Radio Userland, the program favored by Curry, audioblogger Harold Gilchrist and others. Since Radio Userland had a built-in aggregator, it provided both the "send" and "receive" components of what was then called audioblogging. All that was needed for "podcasting" was a way to automatically move audio files from Radio Userland's download folder to an audio player (either software or hardware [1]) -- along with enough compelling audio to make such automation worth the trouble.

While few developers of RSS-capable blogging software or aggregators made use of the enclosure element, in June 2003, Stephen Downes demonstrated aggregation and syndication of audio files in his Ed Radio application. 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 a special RSS-with-enclosures feed for his Harvard Berkman Center colleague Christopher Lydon's weblog, which previously had a text-only RSS feed. Lydon, a former New York Times reporter and NPR talkshow host, had posted 25 in-depth interviews with bloggers, futurists and political figures, which Winer gradually released to the feed. Announcing the feed in his weblog, Winer challenged other aggregator developers to support this new form of content and provide enclosure support. Not long after, Pete Prodoehl released a skin for the Amphetadesk aggregator that displayed enclosure links.

A month later, in October of 2003, Winer and friends organized the first Bloggercon weblogger conference at Berkman Center. CDs of Lydon's interviews were distributed as an example of the high-quality MP3 content enclosures could deliver; Bob Doyle demonstrated the portable studio he helped Lydon develop; Harold Gilchrist presented a history of audioblogging, including Curry's early role, and Kevin Marks demonstrated a script to download RSS enclosures and pass them to iTunes for transfer to an iPod. Curry and Marks discussed collaborating. After the conference, Curry offered his blog readers an RSStoiPod script that moved mp3 files from Userland Radio to iTunes, and encouraged other developers to build on the idea. The iPodder idea was picked up by multiple developer groups. While many of the early efforts remained command-line based, the first podcasting client with a user interface was iPodderX, developed by August Trometer and Ray Slakinski and released in mid-September, 2004. Shortly thereafter, another group (iSpider) rebranded their software as iPodder and released it under that name as Free Software.

The term "podcasting" was one of several terms for portable listening to audioblogs suggested by Ben Hammersley in The Guardian on February 12 2004, referring to Lydon's interview programs ("...all the ingredients are there for a new boom in amateur radio. But what to call it? Audioblogging? Podcasting? GuerillaMedia?"). In September of 2004, Dannie Gregoire also used the term to describe the automatic download and synchronization of audio content; he also registered several 'podcast' related domains (e.g. podcast.net). The use of 'podcast' by Gregoire was picked up by podcasting evangelists such as Dave Slusher, Winer and Curry, and entered common usage.

In September 2004, Curry launched an ipodder-dev mailing list, then Slashdot had a 100+ message discussion, bringing even more attention to the ipodder developer projects in progress at SourceForge. By October 2004, detailed how-to podcast articles had begun to appear online, and a month later, liberated syndication libsyn launched what was apparently the first Podcast Service Provider, offering storage, bandwidth, and RSS creation tools.

In Feburary 2005, Australians Cameron Reilly and Mick Stanic started what was the first Commercial Podcast Network, The Podcast network. Reilly described his vision for the network to be the Time Warner of New media. In November of 2005, they signed a Network wide sponsorship deal with Motorola.

Precursor

Prior to the Internet, in the 1970s, RCS, Radio Computing Services, provided music and talk related software to radio stations in a digital format. Prior to online music digital distribution, the midi format as well as the Mbone, Multicast Network was used to distribute audio and video files. The MBone was a multicast network over the Internet used primarily by educational and research institutes, but there were audio talk programs.

Many other jukeboxes and websites in the mid 1990's provided a system for sorting and selecting music or audio files, talk, segue announcements of different digtal formats. There were a few websites that provided audio subscription services.

The development of downloaded music did not reach a critical mass until the launch of Napster, another system of aggregating music, but without the subscription services provided by podcasting or video blogging aggregation client or system software.

Independent of the development of podcasting via RSS, a portable player and music download system had been developed at Compaq Research as early as 1999 or 2000. Called PocketDJ, it would have been launched as a service for the Personal Jukebox or a successor, the first hard-disk based MP3-player.

A fully-conceived precursor to podcasting came from another early MP3 player manufacturer. To supply content for its players the I2Go company, makers of the eGo player, introduced a digital news service called MyAudio2Go.com that created daily audio news feeds users could download to the eGo or any other MP3 player. The eGo's file transfer application could be programmed to pull down specific feeds to a user's PC every evening.

There were dozens of focused daily feeds covering national news, business news, entertainment news, even a recap of the previous days TV shows. The service lasted over a year, but succumbed when the I2Go company ran out of capital during the dotcom crash and folded. Archive.org has an August 2000 snapshot of the MyAudio2Go site.

In 2001, Applian Technologies of San Francisco, CA introduced Replay Radio, a TiVo-like recorder for Internet Radio Shows. Besides scheduling and recording audio, one of the features was a Direct Download link, which would scan a radio publishers site for new files and copy them directly to a PC's hard disk. The first radio show to publish in this format was Web Talk Guys, produced by Rob and Dana Greenlee.

Popularization

The word about podcasting rapidly spread through the already-popular weblogs of Curry, Winer and other early podcasters and podcast-listeners. Fellow blogger and technology columnist Doc Searls began keeping track of how many "hits" Google found for the word "podcasts" on September 28 2004. On that day, the result was 24 hits. There were 526 hits on September 30, then 2,750 three days later. The number doubled every few days, passing 100,000 by October 18. A year later, Google found more than 100,000,000 hits on the word "podcasts."

On October 11 2004 the first phonetic search engine for podcasting was launched called Podkey to assist podcasters to easily connect to each other. Capturing the early distribution and variety of podcasts was more difficult than counting Google hits, but before the end of October, The New York Times had reported podcasts across the United States and in Canada, Australia and Sweden, mentioning podcast topics from technology to veganism to movie reviews. USA Today told its readers about the "free amateur chatfests" the following February , profiling several podcasters, giving instructions for sending and receiving podcasts, and including a "Top Ten" list from one of the many podcast directories that had sprung up. The newspaper quoted one directory as listing 3,300 podcast programs in February, 2005.

Those Top Ten programs gave further indication of podcast topics: four were about technology (including Curry's Daily Source Code, which also included music and personal chat), three were about music, one about movies, one about politics, and—at the time number 1 on the list—The Dawn and Drew Show, described as "married-couple banter," a program format that USA Today noted was popular on American broadcast radio in the 1940s. After Dawn and Drew, such "couplecasts" became quite popular among independent podcasts (those not derived from a preexisting radio show).

In February 2005, podcasting networks started to appear on the scene with podcasters affiliating with one another. The first was the Tech Podcasts Network, followed by the Association of Music Podcasters and others.

In March of 2005, John Edwards became the first national-level US politician to hold his own podcast. Within a few episodes, the show had all the features of a major podcast: a web site with subscription feeds and show notes, guest appearances, questions from the audience, reviews and discussion of books, musical interludes of podsafe (noninfringing) songs, light banter (sports and recreation talk), even limited soundseeing from on location. Later in the summer of 2005, U.S. President George W. Bush became a podcaster of sorts, when the White House website added an RSS 2.0 feed to the previously downloadable files of the president's weekly radio addresses.

In May 2005 the first book on podcasting was released, the award-winning Podcasting The Do it Yourself Guide, by Todd Cochrane

By mid-2005, the medium had acquired backlash. Some experienced Internet users declared podcasting to be either nothing special (just a variant of blogs and mp3s), or already past its peak (because of growing exposure, and/or adoption by unsavvy Internet users).

In June, 2005, Apple staked its claim on the medium by adding podcasting to its free iTunes 4.9 music software and building a directory of podcasts at its iTunes Music Store. The new iTunes could subscribe to, download and organize podcasts, which made a separate aggregator application unnecessary for many users. Apple also promoted creation of podcasts using its GarageBand and Quicktime Pro software and the MPEG 4, m4a audio format instead of mp3.

In July 2005 the first People's Choice Podcast Awards were held during Podcast Expo. Awards were given in 20 categories.

As is often the case with new technologies, pornography has become a part of the scene, producing what is sometimes called podnography. Other approaches include enlisting a class full of MBA students to research podcasting and compare possible business models, and venture capital flowing to influential content providers.

The growing popularity of podcasting introduced a demand for music available for use on the shows without significant cost or licensing difficulty. Out of this demand, a growing number of tracks, by independent as well as signed acts, are now being designated "podsafe". (See also Podcasting and Music Royalties.)

In September 2005, the first podcast encoded in 5.1-channel encoded Dolby Headphone was created by Revision3 Studios with their 14th episode of Diggnation. The Dolby encoding lasted for only a few minutes of the podcast. On October 12, 2005 Apple Computer CEO Steve Jobs unveiled the first iPod with video capabilty. In his keynote speech he demonstrated the video podcasts Tiki Bar TV and Rocketboom. On December 3, 2005 Sony Computer Entertainment America announced that the PlayStation Portable would support podcasting using the RSS Channel feature after upgrading to 2.60.

In November 2005 the Podcast News Network was launched that focuses on news and world events to include Sports, Business, Lifestyle, Politics, Religion and World and US National News.

"Podcast" was named the word of the year in 2005 by the New Oxford American Dictionary and would be in the dictionary in 2006.

The term "podmercial" was coined in early 2005 by John Iaisuilo, a radio broadcaster/podcaster in Las Vegas, who promptly trademarked it. The term "poditorial" was coined by author John Hedtke in July 2005 while writing half of "Podcasting Now: Audio Your Way!"

In February 2006 the first official Guiness World Record for most popular podcast was awarded to The Ricky Gervais Show. The show, produced by the Guardian Unlimited and hosted by Positive Internet maintained an average of over a quarter of a million downloads per weekly episode.

Adoption by traditional broadcasters

Main article: Podcasting by traditional broadcasters

Traditional broadcasters were extremely quick to pick up on the podcasting format, especially those whose news or talk formats spared them the complications of music licensing. While there had been experimental feeds of radio broadcast material, such as Dave Slusher's August 2004 feed of WREK programs from Georgia Tech, the American syndicated radio show Web Talk Radio apparently became the first to adopt the format on a regular basis, in September 2004, followed within weeks by Seattle news radio station KOMO and by individual programs from KFI Los Angeles and Boston's WGBH.

The BBC began a trial in October 2004 with BBC Radio Five Live's Fighting Talk. These trials were extended in January 2005 to BBC Radio 4's In Our Time. Also in January 2005, CBC Radio began a trial with its weekly national science and technology show Quirks and Quarks, which has offered listeners Real Audio, MP3 and OGG downloads since February 1996. The CBC trial also included CBC Radio 3's Canadian Music Podcast as well as limited podcasting of CBLA's popular Metro Morning Toronto show. United States National Public Radio member stations WNYC and KCRW adopted the format for many of their productions. March saw Virgin Radio become the first UK radio station to produce a daily podcast of its popular breakfast show. In April 2005 the BBC announced it was extending the trial to twenty more programs, including music radio and in the same month Australia's ABC launched a podcasting trial across several of its national stations. In May, Sydney station 2MBS became the first Australian community radio station to deliver content via the format, when its Ultima Thule ambient music programme was made available as a podcast.

In late March, 2005, the trend began to go the other way, with podcasts becoming a source of content for broadcast radio programs by Leo Laporte, Christopher Lydon and others. On March 30 Sirius Satellite began playing Wichita Rutherford's podcast 5 Minutes with Wichita making him the first person who started out as a podcaster to find a home on Satellite Radio. The entire format of KYOU Radio, a San Francisco radio station, became based around broadcasting Podcasts. That summer, when the Canadian Broadcasting Corporation locked out more than 5,000 of its regular on-air and technical staff, they responded by creating their own unofficial podcast of original programming, CBC Unplugged, which also appeared on some campus and community radio stations, including CIUT in Toronto and CFRU in Guelph, Ontario.

London's LBC 97.3 has launched the s first paid-for podcasting service [2]. Subscribers get access to extra podcast channels and the use of an online podcast player similar to the BBC's Listen Again service. The technology used by LBC marks a watershed in podcasting, which had been almost an entirely free phenomenon. Other broadcasters, anxious to generate some revenue to cover the costs of podcasting, may follow.

Coping with growth

While podcasting's innovators took advantage of the sound-file synchronization feature of Apple Computer's iPod and iTunes software -- and included "pod" in the name -- the technology was always compatible with other players and programs. Apple was not actively involved until mid-2005, when it joined the market on three fronts: as a source of "podcatcher" software, as publisher of a podcast directory, and as provider of tutorials on how to create podcasts with Apple products GarageBand and Quicktime Pro. Apple president Steve Jobs demonstrated creating a podcast during his January 10, 2006 keynote address to the Macworld Conference & Expo using new "podcast studio" features in GarageBand 3.

File:Itunespodcast.png

Podcasts in the iTunes Music Store

When it added a podcast-subscription feature to its June 28, 2005, release of iTunes 4.9, Apple also launched a directory of podcasts at the iTunes Music Store, starting with 3,000 entries. Apple's software enabled AAC encoded podcasts to use chapters, bookmarks, external links, and synchronized images displayed on iPod screens or in the iTunes artwork viewer. Two days after release of the program, Apple reported one million podcast subscriptions.

Some podcasters found that exposure to iTunes' huge number of downloaders threatened to make great demands on their bandwidth and related expenses. Possible solutions were proposed, including the addition of a content delivery system, such as liberated syndication; Podcast Servers;Akamai; a peer-to-peer solution, BitTorrent; or use of free hosting services, such as those offered by Ourmedia, BlipMedia and the Internet Archive.

As of September 2005, a number of services began featuring video-based podcasting including Apple, via its iTunes Music Store, Participatory Culture Foundation and Loomia. Known by some as a vodcast, the services handle both audio and video feeds.

Since the release of Apple's 5th Generation iPod in October 2005, which incorporated playing video files, Video Podcasting has become a major selling point for Apple.

Other uses

Podcasting's initial appeal was to allow individuals to distribute their own "radio shows," but the system is increasingly used for other reasons, including:

• A way for people and organizations to avoid regulatory bodies, such as the British Ofcom, that would not allow a program to be broadcast in traditional media.
• A way for news organizations to distribute audio as an addition to their existing text (or mostly text) news products. For example, Wikinews began to podcast its News Briefs in 2005.
• Education. In 2004 Musselburgh Grammar School pioneered podcast lessons with foreign language audio revision and homework , other pioneers include The Room 208 Podcast, Radio WillowWeb, and Room 613 Talk.

In the second half of 2005, a Communication Studies course at the University of Western Australia (iGeneration: Digital Communication and Participatory Culture) used student-created podcasts as the main assessment item.

• Politics. In the U.S., both major political parties have various podcasts, as do numerous politicians.
• Religion. Godcasting has been used by many religious groups . Many churches produce podcasts of talks and sermons. Disciples with Microphones provides podcasts relating to the Catholic church.
• Unofficial audio tours of museums (musecast).
• Official cultural or historic audio tours of cities ([audisseyguides]).
• Communication from space. On 7 August, 2005. American astronaut Steve Robinson claimed the first podcast from space during the Space Shuttle Discovery mission STS-114 - although there was no subscription feed, merely an audio file that required manual downloading. (transcript & audio).
• Television commentary. Battlestar Galactica writer and executive producer Ronald D. Moore creates commentary podcasts for each new episode of Battlestar Galactica (download audio commentary). Other television shows have since followed suit.
• Sports. In 2005, unofficial podcasts for major sports teams launched, providing fans both in and outside of the teams' direct broadcast areas with on-demand commentary. Pioneers include Cubscast. The Cubscast founders also formed the first city-specific sports podcast network, hosting one podcast for each major Chicago team at Chicagosportscasts.com.
• Conference and meeting alerts. Podcasts can be packaged to alert attendees to agendas, hosted roundtables and daily feedback.
• Advocacy. The 5,500 locked out staff (editors, journalists, technicians, hosts, etc.) of the Canadian Broadcasting Corporation were podcasting news and other programming during August and September of 2005.
• Youth media. Podcasting has become a way for youth media organizations, such as Youth Radio (Youth Radio site), to bring youth perspectives to a wider audience.
• Newspapers. Newspapers use podcasts to brodcast audio content from print interviews and drive traffic to their websites. The San Franciso Chronicle is believed to be the first major daily newspaper to start podcasting using an external website, in Feb 2005. Hong Kong's South China Morning Post was the first to use its own website and the first in Asia, having launched on April 19, 2005
• Academic journal digests: The Society of Critical Care Medicine has a podcast used to update clinicians with summaries of important articles, as well as interviews.
• Public libraries can podcast local publications free of Copyright, offering spoken word alternatives to the visually impaired.
• Law enforcement: The Chicago Police Department has a free video podcast of its half-hour weekly news magazine called "CrimeWatch," which airs on local TV. It documents community policing (CAPS) success stories.

Podcasting and Music Royalties

From the beginning, the use of licensed music in podcasts has been a delicate legal issue.

Regular radio-based podcasts

Regular radio broadcasters' podcasts (and MP3 file downloads without subscription feeds) have run into complications regarding royalties for incidental music on "talk" broadcasts, even when identical programs are "streamed." The broadcasters apparently believe companies that license the music will challenge its use in easily downloaded MP3 files, while "streaming" is closer to a broadcasting model.

For example, when popular U.S. conservative commentator Rush Limbaugh began offering "podcasts" early in 2005, his employer, Premiere Radio Networks, tightened its editing of intro and bumper music, which it previously had allowed on other MP3 files. One effect was to render some of Premiere broadcaster Glenn Beck's podcasts difficult to follow. He would appear to stop mid-sentence and restart in a different thought, because of cuts required to remove royalty-protected music.

The technology used by London's LBC 97.3 for its premium rate podcasting service may be applied in the future to podcasts which contain royalty-sensitive content such as music. As each user must pay a fee to access the audio, this may allow royalties to be distributed to the correct recipients.

Future Licensing Issues

The US Congress is studying possible reforms to the Telecommunications Act of 1996, which may in the future affect broadband and Internet services.

See also

• Autocasting (the automatic generation of podcasts from text-only sources)
• Learncasting (delivering instructional content or academic support)
• List of podcast directories
• Media RSS (a kind of syndication of media files used by Yahoo!)
• MMS Podcast (podcasting to mobile phones using MMS)
• Mobilecast (podcasting to mobile phones)
• Narrowcasting (podcasting is a form of narrowcasting)
• Palmcasting (podcasting to Palm devices like Treo and LifeDrive)
• Photofeed (image podcasting)
• Punchcasting (punching podcasts directly into smartphone devices)
• Samizdat (Soviet-era precursor)
• Soundseeing tour (podcast utilizing ambient noise and descriptions)
• Streaming Media
• Vodcasting/Vidcasting (video-based podcasts)
• Audio Wikinews (Wikinews audio project)

External links

• Podcast 411 A list of podcast directories and search engines.
• ViCasting Podcasting Search
• Podcasters Wiki
• 1999 CNN report on MP3.com Stations Pre-Podcast internet radio stations with a playlist concept.
• PodcastingStats.com Podcasting in Numbers; Statistics, Growth.
• PapoTech Podcast sobre tecnología em Portugues.