Final answer:
A parameter is what accepts a value to modify the behavior of a function. It acts as a placeholder that can be assigned a specific value each time the function is called. This allows the function to perform operations with the given values.
Step-by-step explanation:
A parameter accepts a value to be passed to a function, typically affecting the behavior of that function. Parameters act as placeholders within functions, allowing you to pass different values into a function each time you call it, which can then be used within the function to perform operations or calculations. For example, in a programming function that calculates the area of a rectangle, you might have two parameters: one for the length and one for the width. When the function is called, actual numbers are passed to these parameters to calculate the area specific to the rectangle in question.