The simultaneous transmission of several signals along a single path without any loss of identity of an individual signal. The various signals are input to a multiplexer that is used to allocate a transmission path to the input according to a particular parameter of the signal (see frequency-division multiplexing; time-division multiplexing). The original signals are reconstructed at the receiver by a demultiplexer that is operated so as to synchronize with the multiplexer. The transmission path may use any suitable medium, such as wire, waveguide, optical fibres, or radiowaves. The communication channel chosen is termed a multiplex channel.