A Podcast is a digital medium that consists of an episodic series of audio, video, digital radio, PDF, or ePub files subscribed to and downloaded through web syndication or streamed on-line to a computer or mobile device. Use of the term “podcast” predates the addition of native support for podcasting to the iPod, or to Apple’s iTunes software. Other names for podcasting exists, such as “net cast”, intended as a vendor-neutral term without the loose reference to the Apple iPod. The name is used by shows from the TWiT.tv network.
Digital Audio Broadcasting (DAB) is a digital radio technology for broadcasting radio stations, used in several countries across Europe and Asia Pacific. The purpose of digital radio is to increase the number of radio programs in a given spectrum, to improve the audio quality, to eliminate fading problems in mobile environments, to allow additional datacastingservices, and to decrease the transmission power or the number of transmitters required to cover a region. However, analog radio (AM and FM) is still more popular and listening to radio over IP is growing in popularity.
Media is generally regarded as the main means for mass communication. These two mediums are used for entertainments purposes such as music and talk shows to broadcasting the news, making them easily fall into the media category for the fact that they are a few of the most popular sources of mass communication.
I have also come across a relevant video that sums up digital media on the whole-