physical layer

from The Free On-line Dictionary of Computing (8 July 2008)

physical layer
layer 1

   <networking> Layer one, the lowest layer in the {OSI} seven
   layer model.  The physical layer encompasses details such as
   electrical and mechanical connections to the network,
   transmission of {binary} data as changing voltage levels on
   wires or similar concepts on other connectors, and {data
   rates}.

   The physical layer is used by the {data link layer}.

   Example physical layer {protocols} are {CSMA/CD}, {token ring}
   and bus.

   (2004-06-29)