*... millions "of American adults have listened to podcasts. 29% of those who own MP3 players enjoy Web broadcasts at their leisure. More than 22 million American adults own iPods or MP3 players and 29% of them have downloaded podcasts from the Web so that they could listen to audio files at a time of their choosing. That amounts to ... millions of adults who have tried this new feature that allows internet “broadcasts” to be downloaded onto their portable listening device.

The term “podcasting” emerged in 2004, as people combined the words “iPod” and “broadcasting.” Podcast listeners typically download audio files from the Web onto a computer, transfer the files to a digital audio player (like an iPod), and listen at their leisure. Often, the audio files are posted online in a way that allows software on a person’s computer to detect and download new podcasts automatically (generally via RSS) for transfer to a portable player. " source http://www.pewinternet.org/pdfs/PIP_podcasting.pdf