Halfduplex and Fullduplex:--

Simplex:-
One way Communication
Example:- RADIO, TV receiver, SMS, etc.


HALF DUPLEX:-
++can send and receive but not at a time.
++this was originally used on coaxial cables(10BASE5, 10Base2)
and For ethernet HUBS. because these cannot use fullduplex.
++it uses CSMA/CD method.

FULL DUPLEX:-
++can send and receive at same time.
++copper twisted pair used in Full duplex.
++NO need of CSMA/CD
++No COLLISION.