Functions become more powerful when they can accept input values called parameters. Parameters are specified inside the parentheses when defining the function. Multiple parameters are separated by commas. For example:

def greet(first_name, last_name):
    print(f"Hello, {first_name} {last_name}!")

When calling this function, you must provide the arguments:

greet("John", "Dorian")

This function call will produce "Hello, John Dorian!".