What are the properties and advantages of fiber-optic cabling?

Fiber sends pulses of light through pure glass, giving the longest reach and highest bandwidth of any media and total immunity to EMI/RFI — at the cost of higher price and specialized installation.

Fiber-optic cabling carries data as pulses of light through flexible, extremely thin strands of very pure glass, instead of as electrical signals on copper. That single change is responsible for all of fiber's advantages. A laser or LED at the transmitter encodes bits as light pulses, and the fiber acts as a wave guide — the glass keeps the light trapped inside and traveling down the cable with minimal loss.

Because light is not electricity, fiber is completely immune to EMI/RFI (Electromagnetic and Radio Frequency Interference) and far less affected by attenuation, so it transmits data over longer distances at higher bandwidth than any other networking media. That is why it is chosen for backbones and long point-to-point links.

The trade-offs are cost and complexity: fiber is more expensive than copper and requires specialized skills and equipment to install and terminate (you cannot just crimp it like UTP). This is why, despite its superiority, fiber is reserved for the links that actually need it rather than run to every desk.

Go deeper:

• Network Cabling Explained: Twisted Pair, Coaxial, and Fiber Optics — animated explanation including how light travels down fiber and why it beats copper on reach.

• Optical fiber — Wikipedia — how light is guided through pure glass, giving immunity to EMI and long-distance, high-bandwidth links.