Information can be sent in the form of signals.       Signals can be either analogue or digital.     Analogue       An analogue signal behaves like a wave, its amplitude and or frequency changes continuously.       Analogue signals are affected by external interference (noise).       The quality of analogue signal is less than that of digital.       As the analogue signal picks up noise, it is difficult to distinguish between noise and the signal          at the receiving end.     Digital      Digital signal is a series of on and off pulses (it is made up of 1s or 0s).      Digital signals are not affected by external interference (noise).      As the digital signal travels, it picks up noise. This noise is not enough to make a 0 looks like 1.        The signal received is read as the original.      Multiple digital signals can be sent along the same line at the same time, this is multiplexing.