The combination of two or more signals for Transmission along a single wire, path or carrier. The combination of signals for transmission on one optical channel.

Multiplexing occurs when multiple signals are transmitted over a single Fiber and then separated at the receiving end.

There are two main types of multiplexing: Frequency division multiplexing (FDM) and Time Division Multiplexing (TDM).

In frequency division multiplexing each signal travels within its own frequency on a carrier wave which is modulated by Data type and is joined to form a composite signal.

Time division multiplexing uses a single transmission path to carry multiple signals simultaneously. Lower speed signals are time sliced into higher speed signals and are then divided back into single streams once it reaches the receiving end of the line.