The physical layer produces the representation and groupings of bits as voltages, radio frequencies, or light pulses. Various standards organizations have contributed to the definition of the physical, electrical, and mechanical properties of the media available for different data communications. These specifications guarantee that cables and connectors will function as anticipated with different data link layer implementations.

As an example, standards for copper media are defined for the:

The figure shows different types of interfaces and ports available on a 1941 router.