I was in the grocery store the other day. I was alone, so instead of just walking around listening to the store’s music, I decided to turn on my iPod, put in my earbuds and listen to some podcasts.

As I went to check out, the checker asked what I was listening to. “A podcast,” I replied. She looked puzzled. “An internet delivered talk radio show,” I explained. I then went on to tell her that I never listened to the radio anymore. Because of the invention of podcasts I can listen to shows on the topics I want to listen to. It’s really like creating my own talk radio station on the topics that I want to listen to. In my case, they’re primarily tech and more specifically church tech.

That’s really the most basic answer to what a podcast is. That’s the answer I’d give anyone non-techy in my life. “A podcast is an internet delivered talk radio show.” Now, granted some are more music radio than talk, but I tend to listen to the talk shows more.

Now, for the geeky answer. Really a podcast is audio, video, or text content delivered primarily via subscription to an RSS 2.0 feed (with enclosures). Most podcasts tend to be mp3s, but that doesn’t mean there aren’t other types. The iPod enables listeners to subscribe to enhanced aac files which add changing album art, chapter markers, and clickable links (if listened to in iTunes). This format is less prevailant than mp3s, but exist nonetheless, especially among podcasters who use Apple Macintosh computers because of the ease of creating them with the included Garageband software.

Video podcasts are the next most common form. These take the form of mpeg-4 or h.264 video files primarily because of the ability of 5th generation and later iPods to play these video types. Other formats are possible, but are far less common than these. A video podcast might be a simple as a single shot from a single camera, as complex as network television with multiple cameras, highly produced graphics and video packages. In between are a genre called screen casts which are created primarily for computer software instructional purposes. These rely on screen capture software and a talented presenter to pull off well.

Finally, text podcasts are the most rare. These podcasts usually include a pdf document with instructions, plans, an ebook or the like. Authors of podio books (i.e. podcasted audio books) might include the full text of the book for their readers to follow along. An instructional podcast might include step by step instructions that would allow the audience to follow along as the host guides them through a project.

In short, it’s the subscribe-ability that makes a podcast a podcast. Sure people can go to my site to listen to my podcasts, but why do that when you can automatically get all new episodes in iTunes after I release it.

As a side note, you don’t need an iPod to do podcasts. Any mp3 player will do. For that matter you don’t need an mp3 player. You can listen (or watch or read) in your aggregator (i.e. the software that lets you subscribe to podcasts, iTunes being the mose used). Heck, if you wanted to you could burn it to a cd or record it onto audio or video tape. However you listen, watch or read, podcasting is a valuable method of content distribution with a low barrier of entry.