Multiplexors are also known as data selectors. These devices take an  analog or digital input signal and send it to a single output line. Thes  signals are transmitted through a single output line at various speed  and frequencies. These devices act as a multi position switch that take  one input line and transmits to the output. imagine a flashlight with  various brightness levels. these levels are controlled by a resistive  circuit and switched with a manual device that has the same function as a  multiplexor. However, these devices are very fast and efficient.  Typically, the data selection of a multiplexor is controlled by a second  set of input signals called control lines. The binary input of these  control lines will determine the orientation of the output signal. the  advantage of multiplexed displays is that we greatly reduce the amount  of wiring that is necessary.
As seen in the display, input signals S2 and S6 are closed.  Therefore, all of the LEDs in between the two are illuminated. this  indicated the multiplexors completed output circuit. Logic for  multiplexors will be in binary terms indicating a simple on/off for each  input to create a chosen output. Thes work well in timed light displays  to automatically switch outputs based on timed demands. Thes simple  multiplexors circuits can also be used for color changing lights to  determine what signals need to be on to reach a certain output color.