A podcast is a program made available in digital format for download over the Internet. For example, an episodic series of digital audio files that users can download to a personal device to listen to at a time of their choosing. Podcasts are primarily an audio medium, but some distribute video, either as their primary content or as a supplement to audio.

Digital audio is a representation of sound recorded in, or converted into, digital form. In digital audio, the sound wave of the audio signal is typically encoded as numerical samples in a continuous sequence. For example, in CD audio, samples are taken 44,100 times per second, each with 16-bit sample depth. Digital audio is also the name for the entire technology of sound recording and reproduction using audio signals that have been encoded in digital form. Following significant advances in digital audio technology during the 1970s and 1980s, it gradually replaced analog audio technology in many areas of audio engineering, record production and telecommunications in the 1990s and 2000s.