What is the difference between simplex and duplex fiber optic cable?

Simplex Fiber Optic Cable from L-com.com


Simplex Fiber Cable
A simplex fiber cable consists of a single strand of glass of plastic fiber. Simplex fiber is most often used where only a single transmit and/or receive line is required between devices or when a multiplex data signal is used (bi-directional communication over a single fiber).
Duplex Fiber Optic Cable from L-com.com


Duplex Fiber Cable
A duplex fiber cable consists of two strands of glass or plastic fiber. Typically found in a “zipcord” construction format, this cable is most often used for duplex communication between devices where a separate transmit and receive are required.