   #copyright

Podcast

2007 Schools Wikipedia Selection. Related subjects: Websites and the Internet

   An orange square with waves was introduced by Mozilla Firefox to
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   An orange square with waves was introduced by Mozilla Firefox to
   indicate that an RSS feed is present on a webpage. By mutual agreement,
   the same icon has also been adopted by Microsoft Internet Explorer and
   Opera.

   A podcast is a multimedia file distributed over the Internet using
   syndication feeds, for playback on mobile devices and personal
   computers. Like 'radio', it can mean both the content and the method of
   delivery; the latter may also be termed podcasting. The host or author
   of a podcast is often called a podcaster.

   Though podcasters' web sites may also offer direct download or
   streaming of their content, a podcast is distinguished from other
   digital audio formats by its ability to be downloaded automatically
   using software capable of reading feed formats such as RSS or Atom.

History

   The concept of podcasting was suggested as early as 2000 and its
   technical components were available by 2001, then implemented in the
   program Radio Userland . In 2003 regular podcasts started showing up on
   well-known Web sites and software support spread.

Name

   The editors of the New Oxford American Dictionary declared "podcasting"
   the 2005 word of the year, 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".

   The name has aroused some controversy for implying one needs an iPod to
   listen to podcasts, when in fact all portable media players will play
   them. Creative Technology, the makers of iPod competitor Zen, state on
   the ZENcast website that podcast is short for "Personal On Demand
   broadcast", a definition that didn't exist before its use by Creative.

   Some alternate names have been proposed, most recently 'netcast',
   suggested by podcaster and technology journalist Leo Laporte, partly in
   response to cease-and-desist letters sent by Apple to companies and
   individuals using the word 'pod' in their product's names. None of the
   terms has yet received as wide a use as 'podcast.'

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 whereby 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.

   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 list of
   the URLs by which episodes of the show may be accessed. This list is
   usually published in RSS format (although Atom can also be used), which
   provides other information, such as publish date, 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. Standard podcasts consist of a feed from
   one author. More recently multiple authors have been able to contribute
   episodes to a single podcast feed using concepts such as public
   podcasting and social podcasting.

   The content provider posts the feed on a webserver. 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 uses a type of software known as an aggregator, sometimes
   called a podcatcher or podcast receiver, to subscribe to and manage
   their feeds.

   A podcast specific aggregator is usually an always-on program which
   starts when the computer is started and runs in the background. They
   work exactly like any newsreader someone would use to manage other web
   subscriptions. 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 application's list), the program
   determines the location of the most recent item and automatically
   downloads it to the user's computer. Interestingly, it is estimated
   that perhaps only 20% of podcasts are actually consumed on portable
   media players; 80% are consumed on the PC onto which they are
   downloaded, or deleted from the PC without being listened to. Some
   applications, such as iTunes, also automatically make the newly
   downloaded episodes available to a user's portable media player.

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

   To conserve bandwidth, users may opt to search for content using an
   online podcast directory. Some directories allow people to listen
   online and initially become familiar with the content provided from an
   RSS feed before deciding to subscribe. For most broadband users,
   bandwidth is generally not a major consideration; it could fairly be
   stated that podcasting itself is a technology that came with the
   increases in global bandwidth and broadband popularity.

Other uses

   Podcasting's initial appeal was to allow individuals to distribute
   their own "radio shows," but the system quickly became used in a wide
   variety of other ways, including distribution of school lessons,
   official and unofficial audio tours of museums, conference meeting
   alerts and updates, and by police departments to distribute public
   safety messages.

   Retrieved from " http://en.wikipedia.org/wiki/Podcast"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
