A very common requirement of computers is to store and play back recorded sound, which of course includes music.
A 'real' sound is analogue in nature, you listen to sound with analogue ears where tones and rhythms blend together smoothly.
But computers are digital, they can only deal with binary numbers.
Therefore if sound is to be handled by a computer, the analogue sound from any source has to be converted into a set of binary numbers i.e. you 'digitise' the sound with some input device.
This is called 'sampling' the sound.
This section will discuss sampling and related topics in more detail.