Information can be transmitted using analogue or digital signals.
Communications signals can be analogue or digital.
Music and speech vary continuously in frequency and amplitude. In the same way, analogue signals can vary in frequency, amplitude, or both. You may have heard of FM and AM radio - Frequency Modulated radio and Amplitude Modulated radio. The diagram shows a typical oscilloscope trace of an analogue signal.
Digital signals are a series of pulses consisting of just two states: ON (1) or OFF (0). There are no values in between. DAB radio is Digital Audio Broadcast radio - it is transmitted as digital signals. The diagram shows a typical oscilloscope trace of a digital signal.