What is a key characteristic of a function in programming?

A key characteristic of a function in programming is that it returns a value after execution. Functions are designed to perform specific tasks and produce a result based on the input they receive. The return value allows the result of the function to be used later in the program, whether it's for displaying information, making calculations, or passing the value to another function. This characteristic is what distinguishes functions from other programming constructs like procedures, which may perform actions but do not necessarily return a value.

In contrast, while functions can interact with variables, including global variables, that capability does not define what a function is. Additionally, functions typically accept parameters to operate on specific inputs, so executing code without parameters is not characteristic of most functions. Lastly, functions can be called from within procedures, highlighting their versatility and integration in programming structures.