Mutliplexer:
Multiplexer means many into one. A multiplexer is a circuit used to select and route any one of the several input signals to a signal output. An simple example of an non electronic circuit of a multiplexer is a single pole multiposition switch.
Multiplexer handle two type of data that is analog and digital. For analog application, multiplexer are built of relays and transistor switches. For digital application, they are built from standard logic gates.
The multiplexer used for digital applications, also called digital multiplexer, is a circuit with many input but only one output. By applying control signals, we can steer any input to the output. Few types of multiplexer are 2-to-1, 4-to-1, 8-to-1, 16-to-1 multiplexer.
Following figure shows the general idea of a multiplexer with n input signal, m control signals and one output signal.
Demultiplexer:
Demultiplexer means one to many. A demultiplexer is a circuit with one input and many output. By applying control signal, we can steer any input to the output. Few types of demultiplexer are 1-to 2, 1-to-4, 1-to-8 and 1-to 16 demultiplexer.