A MUX, or multiplexer, is an electronic device that selects one of several input signals and forwards the chosen input to a single output line. It acts like a digital switch, allowing multiple data sources to share a single communication channel, which helps in efficient data management and transmission. MUXes are commonly used in various applications, including telecommunications, data routing, and computer systems. They can handle multiple data streams, making them essential in devices like television sets, network routers, and data acquisition systems, where they help streamline the flow of information.