There are three basic forms of network media. The physical layer produces the representation and groupings of bits for each type of media as:
- Copper cable: The signals are patterns of electrical pulses.
- Fiber-optic cable: The signals are patterns of light.
- Wireless: The signals are patterns of microwave transmissions.
The figure displays signaling examples for copper, fiber-optic, and wireless.
To enable physical layer interoperability, all aspects of these functions are governed by standard organizations.