A podcast is an episodic series of digital media files which a user can set up so that new episodes are automatically downloaded via web syndication to the user’s own local computer or portable media player. The word arose as a portmanteau of “iPod” (a brand of media player) and “broadcast”. Thus, the files distributed are typically in audio or video formats, but may sometimes include other file formats such as PDF or ePub.

The distributor of a podcast maintains a central list of the files on a server as a web feed that can be accessed through the Internet. The listener or viewer uses special client application software on a computer or media player, known as a podcatcher, which accesses this web feed, checks it for updates, and downloads any new files in the series. This process can be automated so that new files are downloaded automatically, which may seem to the user as though new episodes are broadcast or “pushed” to them. Files are stored locally on the user’s device, ready for offline use. Podcasting contrasts with webcasting or streaming which do not allow for offline listening, although most podcasts may also be streamed on demand as an alternative to download. Many podcast players (apps as well as dedicated devices) allow listeners to adjust the playback speed.

Some have labeled podcasting as a converged medium bringing together audio, the web, and portable media players, as well as a disruptive technology that has caused some people in the radio business to reconsider established practices and preconceptions about audiences, consumption, production, and distribution. Podcasts are usually free of charge to listeners and can often be created for little to no cost, which sets them apart from the traditional model of “gate-kept” media and production tools. It is very much a horizontal media form: producers are consumers, consumers may become producers, and both can engage in conversations with each other.

“Podcast” is a portmanteau, invented by BBC journalist Ben Hammersley in 2004, of the words “pod” — from iPod, a popular brand of portable media player produced by Apple Inc. — and “broadcast”. Despite the etymology, the content can be accessed using any computer or similar device that can play media files. Use of the term “podcast” predated Apple’s addition of formal support for podcasting to the iPod, or to Apple’s iTunes software.

Other names for podcasting include “net cast”, intended as a vendor-neutral term without the loose reference to the Apple iPod. The name is used by shows from the TWiT.tv network. Some sources have suggested the backronym “portable on demand” for “POD”, for similar reasons.

Many people and groups, including Dawn and Drew of The Dawn and Drew Show, Kris and Betsy Smith of Croncast, and Dan Klass of The Bitterest Pill contributed to the early emergence and popularity of podcasts. Former MTV VJ Adam Curry, in collaboration with Dave Winer, a developer of RSS feeds, is credited with coming up with the idea to automate the delivery and syncing of textual content to portable audio players.

Podcasting, once an obscure method of spreading information, has become a recognized medium for distributing audio content, whether for corporate or personal use. Podcasts are similar to radio programs, but they are audio files. Listeners can play them at their convenience, using devices that have become more common than portable broadcast receivers.

The first application to make this process feasible was iPodderX, developed by August Trometer and Ray Slakinski. By 2007, audio podcasts were doing what was historically accomplished via radio broadcasts, which had been the source of radio talk shows and news programs since the 1930s. This shift occurred as a result of the evolution of internet capabilities along with increased consumer access to cheaper hardware and software for audio recording and editing.

In August 2004, Adam Curry launched his show Daily Source Code. It was a show focused on chronicling his everyday life, delivering news and discussions about the development of podcasting, as well as promoting new and emerging podcasts. Daily Source Code is believed to be the first podcast produced on a consistent basis. Curry published it in an attempt to gain traction in the development of what would come to be known as podcasting and as a means of testing the software outside of a lab setting. The name Daily Source Code was chosen in the hope that it would attract an audience with an interest in technology.

Daily Source Code started at a grassroots level of production and was initially directed at podcast developers. As its audience became interested in the format, these developers were inspired to create and produce their own projects and, as a result, they improved the code used to create podcasts. As more people learned how easy it was to produce podcasts, a community of pioneer podcasters quickly appeared. Despite a lack of a commonly accepted identifying name for the medium at the time of its creation, Daily Source Code is commonly believed to be the first podcast to be published online.

In June 2005, Apple released iTunes 4.9 which added formal support for podcasts, thus negating the need to use a separate program in order to download and transfer them to a mobile device. While this made access to podcasts more convenient and widespread, it also effectively ended advancement of podcatchers by independent developers. Additionally, Apple issued Cease and Desist orders to many podcast application developers and service providers for using the term “iPod” or “Pod” in their products’ names.

Within a year, many podcasts from public radio networks like the BBC, CBC Radio One, National Public Radio, and Public Radio International placed many of their radio shows on the iTunes platform. In addition, major local radio stations like WNYC in New York City and WHYY-FM radio in Philadelphia, KCRW in Los Angeles placed their programs on their websites and later on the iTunes platform.

Concurrently, CNET, This Week in Tech, and later Bloomberg Radio, the Financial Times, and other for-profit companies provided podcast content, some using podcasting as their only distribution system.

Podcast novels

A podcast novel (also known as a serialized audiobook or podcast audiobook) is a literary format that combines the concepts of a podcast and an audiobook. Like a traditional novel, a podcast novel is a work of long literary fiction; however, this form of the novel is recorded into episodes that are delivered online over a period of time and in the end available as a complete work for download. The episodes may be delivered automatically via RSS, through a website, blog, or another syndication method. These files are either listened to directly on a user’s computer or loaded onto a portable media device to be listened to later.

The types of novels that are podcasted vary from new works from new authors that have never been printed, to well-established authors that have been around for years, to classic works of literature that have been in print for over a century. In the same style as an audiobook, podcast novels may be elaborately narrated with separate voice actors for each character and sound effects, similar to a radio play. Other podcast novels have a single narrator reading the text of the story with little or no sound effects.

Podcast novels are distributed over the Internet, commonly on a weblog. Podcast novels are released in episodes on a regular schedule (e.g., once a week) or irregularly as each episode is released when completed. They can either be downloaded manually from a website or blog or be delivered automatically via RSS or another method of syndication. Ultimately, a serialized podcast novel becomes a completed audiobook.

Some podcast novelists give away a free podcast version of their book as a form of promotion. Some such novelists have even secured publishing contracts to have their novels printed. Podcast novelists have commented that podcasting their novels lets them build audiences even if they cannot get a publisher to buy their books. These audiences then make it easier to secure a printing deal with a publisher at a later date. These podcast novelists also claim the exposure that releasing a free podcast gains them makes up for the fact that they are giving away their work for free.

Video podcasts

A video podcast (sometimes shortened to “vodcast”) includes video clips. Web television series are often distributed as video podcasts.

Dead End Days (2003–2004) is commonly believed to be the first video podcast. That serialized dark comedy about zombies was broadcast from 31 October 2003 through 2004.

Since the spread of the Internet and the use of Internet broadband connection TCP, which helps to identify various applications, a faster connection to the Internet has been created and a wide amount of communication has been created. Video podcasts have become extremely popular online and are often presented as short video clips, usually excerpts of a longer recording. Video clips are being used on pre-established websites, and increasing numbers of websites are being created solely for the purpose of hosting video clips and podcasts. Video podcasts are being streamed on intranets and extranets, and private and public networks, and are taking communication through the Internet to whole new levels.

Most video clips are now submitted and produced by individuals.[not specific enough to verify] Video podcasts are also being used for web television, commonly referred to as Web TV, a rapidly growing genre of digital entertainment that uses various forms of new media to deliver to an audience both reruns of shows or series and content created or delivered originally online via broadband and mobile networks, web television shows, or web series. Examples include Amazon, Hulu, and Netflix. Other types of video podcasts used for web television may be short-form, anywhere from 2–9 minutes per episode, typically used for advertising, video blogs, amateur filming, journalism, and convergence with traditional media.

Video podcasting is also helping build businesses, especially in the sales and marketing sectors. Through video podcasts, businesses both large and small can advertise their wares and services in a modern, cost-effective way. In the past, big businesses had better access to expensive studios where sophisticated advertisements were produced, but now even the smallest businesses can create high-quality media with just a camera, editing software, and the Internet.

Oggcast

An oggcast is a podcast recorded and distributed exclusively in the Ogg vorbis audio codec and/or other similarly free codecs. For example, a podcast distributed both in the non-free MP3 format and the free Ogg Vorbis format would not technically meet the definition of an oggcast. In contrast, a podcast distributed in both the Ogg Vorbis and Speex codecs would meet the strict definition of an oggcast. The term oggcast is a combination of the word “ogg” from the term Ogg Vorbis, and the syllable “cast”, from “broadcast”.

The exact timeline of the term oggcast is uncertain. However, The Linux Link Tech Show, one of the longer running Linux podcasts still in production, has a program in the Ogg Vorbis format in its archives from January 7, 2004. Given that a stable release of Ogg Vorbis did not appear until July 19, 2002, it is very likely that the term oggcast was coined sometime between 2002 and 2004.

Oggcasters tend to be broadcasters who prefer not to use audio and video codecs that have patent and/or licensing restrictions, such as the MP3 codec.

Recording and distributing podcasts in the Ogg Vorbis audio format has advantages. Mozilla Firefox and Google Chrome web browsers both support playing Ogg Vorbis files directly in the browser without requiring plugins. Ogg Vorbis may produce better audio quality with a smaller file size than alternative codecs such as AAC or MP3. However, this has not been proven conclusively. Ogg Vorbis is not bound by patents and is considered “free software” in the sense that no corporate entity owns the rights to the format. Some people feel that this is a safer container for their multimedia content for this reason. However, Oggcasters can generally not reach as wide of an audience as more traditional podcasters. This is mainly due to the lack of native Ogg Vorbis support in Microsoft’s Internet Explorer and Apple’s Safari web browser, and the lack of Ogg Vorbis support in many mobile audio devices.

Oggcast planet maintains a central list of oggcasts.

Political podcast

A political podcast focuses on current events, lasts usually a half hour to an hour, often with a relaxed and conversational tone, and features journalists and politicians and pollsters and writers and others with credentials in the public sphere. Most political podcasts have a host-guest interview format and are broadcast each week based on the news cycle. Political podcasts have blossomed in the past few years in the United States because of the long election cycle.