A “podcast” is sort of difficult to explain because there really isn’t anything else like it — but rather, many things that are kind of like it.

A good starting point is to think of a podcast as “Internet Radio On-Demand.”  It’s similar in that you can usually listen to it on your computer — but it’s more than that.  However, and not to confuse the issue, podcasting isn’t confined to just audio but can be video as well.

It has well over 100,000 content specific “channels,” which are sure to suit just about anyone’s interests, and is available on the Internet.  So, in a sense, it’s kind of like a Library.

RSS FeedWith the amount of content that podcasting provides, regular Broadcast Radio, or “Terrestrial Radio” — as they call it — simply can never compete.  The AM and FM radio band only has so many channels.  Consequently, radio stations “Broadcast” their content — meaning that they attempt to appeal to as broad of an audience as possible.  Because, afterall, this is what advertisers are looking for.  But podcasting, by contrast, is not necessarily hamstrung to advertising revenue like its broadcasting cousin.  With its specific and specialized content, it is able to “narrowcast” to only those who choose to listen.  So while a particular podcast’s audience may be considerably smaller than the audience of a broadcast, one could argue that the podcast’s audience is a much more targeted and interested in the content being delivered.  So, in a way, Satellite Radio, with its ability to provide more channels than Broadcast Radio, takes a step towards podcasting — but still does not come close.

Podcasts are “On Demand” and can be listened to on your schedule — not when a Radio Station decides to air it.  So, it’s kind of like TiVo.

Each podcast has a website it calls “home” (like ours at www.theentrepreneursradioshow.com) where show episodes can be listened to or downloaded for future listening.  With downloaded media, you can either listen to it on your computer or take it with you by transferring it to an iPod or any other portable digital media player.  So, in this way, it’s kind of like a small paperback book.

Also read: How to Subscribe to a Podcast in iTunes?

But what truly makes a podcast unique, and what gives a podcast its “casting” ability, is how it is able immediately deliver itself to multiple podcast directory websites (such as iTunes, Podcast Alley, and Podcast Pickle) and Podcatcher applications (like iTunes, Juice, and Zune) through a process of syndication known as RSS (Real Simple Syndication).

Listeners can easily “subscribe” to podcasts (most are free) by clicking on its RSS icon or subscription button (ours is located below each episode). The listener is then walked through how to add that podcast’s syndication “feed” to a podcatching application of their choosing — or even good old-fashioned email.  So, when a podcaster releases a new episode, subscribers are automatically notified without having to constantly check back with the podcast’s website to see if a new show has been produced.  And, with the podcatching software, episodes of their favorite podcasts can be automatically downloaded and, if they choose, transferred to their portable listening device — all without having to lift a finger.  So, in this way, podcasts are like magazine subscriptions.

Podcasts can be produced by just about anyone wanting to share and communicate with the world.  They are not exclusive to Big Name Media.  So, you could also say that podcasts are like Blogs.

Because podcast websites usually have ways for listeners to leave comments about each episode, and literally enter into a discussion with other listeners, podcasts are like a community of individuals sharing a common interest.  And with an estimated 47 million podcast listeners out there in 2010, that’s a pretty hefty community.

Reference: http://spinalcolumnradio.com/whats-a-podcast/
Also read: How to Subscribe to a Podcast in iTunes?