Sound recording can be split into two main sections such as analog recording or digital recording.
Analog recording is when a microphone diaphragm detects changes in atmospheric pressure that is caused by sound waves. These signals can be stored as a mechanical representation of the sound waves on mediums such as a gramophone record, or in plastic tape with magnetic coating on it. (magnetic tape)
Digital recording is when sound waves that are picked up by the microphone diaphragm are converted to a digital signal. It is done through a process called sampling and stored as binary numbers (ones and zeros), which represents every sample of the amplitude of the audio signal at equal time intervals. For example; a sample rate of 44.1 kHz means that samples of the audio signal are recorded at 44100 times per second.