Podcasting is the relay of information through audio. Rather than read an article or watch a video, your target audience will listen to your pre-recorded "internet radio show" as you provide content on topics of interest to them.
Once your podcast is recorded, it can be broadcast to a wider audience in a number of ways. It can be listed in directories so it can be discovered and listened to. It can also be broadcast to other websites and listened to anytime, anywhere, by people who subscribe to your podcast.