Digital
From DNBWiki
Analogue signals have (like every real word signal) a frequency bandwith and noise. When a signal has a bandwidth, the rate at witch it can change is limited, and the changes themselves become predictable. So, when a waveform can only change between samples in 1 way, it is then only necessary to get the samples and the original waveshape can be reconstructed from them.
Digital is simply a different way of carrying the same information. The conversion from an analogue to a digital signal is called sampling, i.e. gathering the amplitude of the analogue signal at fast intervals, and storing them as a series of numbers. That numbers represent a waveshape offers many advantages, most dramatically the ability to use software to work with audio, instead of a room of full sized specialist hardware. The rate at which a digital system gathers data about the incoming fluctuations of voltages is measured in two ways; the sample rate and bit depth.
The reason many people consider analogue "better" is because of its subtle distortions. The distortions that analogue circuits produce sound "warm" to humans see (this is because of some circuit elements, valves for example, produce distortion in the frequency range that is a multiple of the original sound's frequency - causing harmonic distortion, also found in tube compressors).
Because distortion is a nonlinear process its very difficult to emulate correctly, but advancements in technology continue to get closer to that characteristic sound, with only the most experienced ears being able to tell the difference between some of the better emulations.
