 This lesson is called Songwriting with Parameters. We're going to be writing some songs here. Sometimes the chorus is just a little bit different each time you sing it. Do you remember Old MacDonald had a farm? The chorus is slightly different for each animal. This small change in each chorus can be shown using something that we call parameters. Sometimes a function needs a parameter. A parameter is an extra piece of information that you can pass to a function to customize it for a special need. When you make ice cream sundaes for your friends, you are using a process similar to functions and parameters in a computer program. The dish of vanilla ice cream might be the same for every sundae, but when you ask your friend which two toppings they'd like, you could get lots of different combinations. Topping is the function name, but each type of topping is a parameter. Functions and parameters work together to make great computer programs and great sundaes too.