What is a value parameter in a function or procedure definition?

A value parameter in a function or procedure definition is indeed a copy of the value passed to the function at the time of its call. This means that when a function is invoked, a duplicate of the argument is created, and any modifications made to this value parameter within the function do not affect the original argument outside the function.

This concept is essential in understanding how data is passed within programming: since the function works with a copy of the data, it ensures that the original values remain unchanged unless explicitly modified by some other means. This leads to safer and more predictable function behavior, as the internal workings of the function do not have unintended side effects on the context from which it was called.

Other options, while related to programming, do not accurately describe the nature of a value parameter. For instance, changing original values or defining data types are characteristics related to different parameter types or program structures, but do not reflect the fundamental idea of how value parameters operate.