What is a mux device?

Can you explain what a mux device is, and how it is used in the context of cryptocurrency and finance? I'm curious to know if it's a hardware device or a software tool, and what specific functions or advantages it offers in this field. Additionally, is it a widely adopted technology in the cryptocurrency industry, or is it still a relatively niche concept? Understanding the basics of a mux device and its applications would be very helpful in gaining a deeper insight into the cryptocurrency landscape.