Podcasting is a means of distributing audio and video programs via the Internet that lets users subscribe to a number of “feeds,” and then hear or view the material at the time they choose. A feed is usually in the MP3 audio format.
“Podcasting” is distinct from other types of online media delivery because of its subscription model, rather than one-time delivery. A series of files are delivered because subscribers want to get the information regularly.
For your computer, the simplest software to use is iTunes (can be downloaded for free here)