Multiplexes 2 to 16 inputs to a single output. The inputs and outputs and can be configured as buses or single bits. The multiplexer symbol includes an indication of which input is currently selected.
The value of the input pin or bus determines which input is routed to O. The input will be a single bit if there are two choices (binary) or a bus if there are more than 2 choices.
The top example has been configured as a two input bus multiplexer. Since there are only two possible inputs, the selector input is a single bit. A value of true selects input I1.
The second example has been configured as an eight input bit multiplexer. The bus input is set to a value of 101 (5) so input I5 is selected to the output.