Wikipedia
Podguide
A podguide is an enhanced audio tour podcast. It is a single audio file where each chapter displays a picture and a number of what to look at a certain stopover. The numbers correspond to the numbers on a map that can be downloaded via the link incorporated into the artwork of the chapters in the podguide. Podguides are in the m4a format and can only be listened to through iTunes or an iPod. It is like a soundseeing tour but with pictures and a map, so users can take the tour themselves.