What is the difference between an argument and a parameter variable?

A parameter variable is a variable used within the function declaration to represent the input data that the function will receive when it is called. It acts as a placeholder for the data that will be passed into the function.

An argument is the actual value or variable that is passed into a function when it is called. The argument corresponds to the parameter variable in the function declaration and replaces the placeholder with the given data.

Let's consider a simple example of a function called multiply that has two parameter variables 'a' and 'b' and returns the product of those variables. ```python def multiply(a, b): return a * b ``` In this example, 'a' and 'b' are parameter variables, representing the inputs the function will receive when it is called. Now, let's say we want to call the function to calculate the product of 5 and 6. We can do this by providing the values 5 and 6 as arguments: ```python result = multiply(5, 6) ``` In this case, 5 and 6 are the arguments that we pass to the function call, replacing the parameter variables 'a' and 'b' respectively. The function returns the product of 5 and 6, and stores the result in the variable 'result'.