What is podcasting?
Technically, podcasting is the distribution of audio (and sometimes video) episodes or segments through an RSS feed (the RSS popularized by blogs).
Subscribers to the RSS feed can either use a regular RSS client, such as Firefox (in its latest versions), or a dedicated podcast client, such as iTunes. Podcasting shines with dedicated clients because they download the audio/video episodes when the computer is idle. Dedicated clients can also synchronize with MP3 players (the "pod" in podcast stands for the iPod, the most popular MP3 player), allowing listeners to listen to episodes in the car/metro/train/plane or while jogging, exercising, or shopping.
You do not need an MP3 player to enjoy podcasts. I work from my home office and listen to podcasts mostly on my desktop, although I enjoy listening on an iPod while traveling by train to a customer or a conference.
Many less technical definitions of podcasting have been proposed: radio-on-demand (the listener chooses when to consume the episodes), portable Web (the listener can carry Web episodes on an MP3 player), audio blog (combining a blog with audio features), the renaissance of free radio (podcasts are usually produced by amateurs). Each of these definitions carries some truth...which shows that podcasting is a significant evolution for the Web.
What is being discussed in podcasts? Anything really. You can find podcasts on software development (right here, at developerWorks), movie reviews, wine tasting, photography, comedy, personal matters (audio blogs) and, of course, music! Unlike radio, there are no strict rules to adhere to because anybody with a microphone and a computer can give it a go.
A good selection of podcasts is available at many online directories. The most popular directory is the iTunes Music Store; other popular directories include PodcastAlley, Yahoo! Podcast, and Odeo (see Resources).