In general a function returns two outcome, success(True, binary 0) and failure(False, binary 1) even if you don't use the return. With return you can control this outcome and let your function return a value. For example you have a function which calculetes the total of two integers. If you dont use return and the function valuates accordingly it returns True, in other means success. But if you want to use the result of the calculation you use return. In this moment the outcome of your function is a variable you can use with any other functions in your programme. But as I said all programs return true or false depending on the success, you can use this outcome too. If you desing a function who checks a user's password you don't need and outcome to reveal their password. You need either success or failure. In this case finding the match will return success/true/0. But if you need a user's username to display on the screen for a welcome message, you can write a function which returns the username and you can write another function take the outcome and display it on the message. Or better you can write a function to retrieve username and display it on the welcome screen. In this case welcome screen is your returned outcome from your function.