Transmission media/medium

The transmission medium is the physical path between transmitter and receiver.

Transmission and reception of data is performed in four steps:
   1-the data is coded as binary numbers at the sender end;
   2-a carrier signal is modulated as specified by the binary representation of the data
   3-at the receiving end, the incoming signal is demodulated into the respective

binary numbers; and 

   4- decoding of the binary numbers is performed.

A physical medium in data communications is the transmission path over which a signal propagates. Many transmission media are used as communications channels.