Podcasting is becoming one of the best forms of communication. Basically a podcast (style cast) is like a mini radio or television programme which can be viewed on a computer mp3 player (iPod or similar) or, mobile telephone*.
The real beauty is, when you "subscribe" (free of charge) you don't ever need to check for the latest episode, it is automatically delivered to your computer when it becomes available, so you will never miss an episode.
Once the file is on your computer you can view it or elect to send it to your mp3 player or mobile telephone to listen to, or watch, when it suits you.