"Podcasting" is making
audio files (most commonly in MP3 format) available online in a
way that allows software to automatically download the files for
listening at the user's convenience.
The word "podcasting" is a portmanteau
of the words iPod and broadcasting. A podcast is like an audio
magazine subscription: a subscriber receives regular audio programs
delivered via the internet, and they can listen to them at their
Podcasts differ from traditional internet audio
in two important ways. In the past, listeners have had to either
tune in to web radio on a schedule, or they have had to search
for and download individual files from webpages. Podcasts are
much easier to get. They can be listened to at any time because
a copy is on the listener's computer or portable music player
(hence the "pod" in "podcasting"), and they
are automatically delivered to subscribers, so no active downloading
Podcasting is functionally similar to the use
of timeshift-capable digital video recorders (DVRs), such as TiVo,
which let users record and store television programs for later
Podcasting was developed in part thanks to
former MTV VJ, Adam Curry's original iPodder script and the success
it fostered since August, 2004.
Podcasting was first used to directly describe
the "automatic download and synchronization" idea developed
by Adam Curry by Dannie J. Gregoire on September 15, 2004. Gregoire
had registered the domain names associated with podcasting, podcasting.net.
That usage was discovered and reported on by Dave Slusher of the
Evil Genius Chronicles and Adam Curry.
Adding to a number of ad-hoc, proto-podcasting
techniques for automatically downloading audio files, podcasting
proper became popular through association with blogs (in particular
MP3 blogs), the XML-based file format called RSS (Really Simple
Syndication), and the polling applications called feed readers
or news readers that poll and download RSS files.
Blogs, often being self-published websites,
provided a convenient means for individuals to self-publish audio
files online. RSS already gave websites and blogs a means to summarize
or list new content added to the site. Individuals already used
RSS to poll websites for new content. Thus, the addition of audio
file listings to RSS, and the addition of audio file downloading
to RSS feed readers built upon the feed reader's existing methods
for polling and downloading files, and upon the existing "reader
driven" interaction with content publishers.