How does a NOT gate function?

A NOT gate is a fundamental component in digital logic circuits that performs a specific logical operation: it inverts the input value. This means that if the input to the gate is true (or 1), the output will be false (or 0), and vice versa.

In binary terms, this can be visualized clearly; if the input is represented as '1', the NOT gate transforms it into '0'. Conversely, if the input is '0', the output becomes '1'. This inverting function is crucial in logic circuits because it allows for the manipulation of signals based on their true or false states.

The other options present different operations which do not relate to the behavior of a NOT gate. For example, adding inputs refers to arithmetic operations, which is not applicable in this context, and outputting the same value or multiplying inputs describes different logical operations that are associated with other types of gates, such as AND or OR gates. Therefore, the defining characteristic of a NOT gate is indeed its ability to invert the input value.