Transmitter

Receiver

Medium

Guided Medium: Media in which signal is guided along a physical path. e.g. twisted pair, coax, optical fiber.

 Unguided Medium: Media in which signal is not guided. e.g. air, water, vacuum.

Direct Link 

No intermediate devices

Point to Point

Direct Link

Only 2 devices share link

Multi-point 

More than two devices share link

Simplex

One Direction. e.g. Television

Half Duplex 

Either Direction, but only one way at a time. e.g. Police radio

Full Duplex 

Both directions at the same time. e.g. Telephone