A music download is the digital transfer of music via the Internet into a device capable of decoding and playing it, such as a personal computer, portable media player, MP3 player or smartphone. This term encompasses both legal downloads and downloads of copyrighted material without permission or legal payment. Music downloads are typically encoded with modified discrete cosine transform (MDCT) audio data compression, particularly the Advanced Audio Coding (AAC) format used by iTunes as well as the MP3 audio coding format.

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.