This chapter contains the main principles of digital audio, described in a relatively non-mathematical way. Digital audio systems, on the other hand, convert the electrical waveform from a microphone into a series of binary numbers, each of which represents the amplitude of the signal at a unique point in time. Digital audio can be engineered to be more tolerant of a poor storage or transmission channel than analog audio. Digital audio has made it possible for sound engineers to take advantage of developments in computer industry, and this is particularly beneficial because size of that industry results in mass production (and therefore cost savings) on a scale not possible for audio products alone. Doubling the sampling frequency leads to a doubling in overall data rate of a digital audio system and a consequent halving in storage time per megabyte. It also means that any signal processing algorithms need to process twice the amount of data and alter their algorithms accordingly.