What is MUX?

1) In communication transmission systems, MUX (pronounce muks, sometimes spelled "MUX") is an abbreviation for multiplexing,
A device that sends multiple signals on a carrier channel at the same
Time in the form of a single, complex signal to another device that
Recovers the separate signals at the processing end. The specified er is
Sometimes called Demux(Or "Demux ").

2) on the Internet, a MUX is a multi-user text game played over
Internet, using the tinymux server. This kind of game started with the mud (multi-user dungeon) movement.

To put it simply, it is "multi-channel multiplexing"