Why input a new variable in the While loop?

I'm assuming the code should look like this:

while password != MASTER_PASSWORD: 
    if attempt_count > 3: 
        sys.exit("Too many invalid password attempts") 
    password = input("Invalid password, try again: ")

Remember while loops continue to loop unless password != MASTER_PASSWORD becomes False or the loop is broken in another way (the sys.exit(), a return statement, etc.). Inside of this loop, you are checking how many time someone has attempted to input a correct password. If the number of attempts is greater than 3, then the app exits. You also ask the user to input their password, if it is correct then password != MASTER_PASSWORD becomes Falseand the loop is terminated. If the user inputs an incorrect password, then password != MASTER_PASSWORD is still true and the user is asked for their password again because it was invalid. This continues until the user either uses up all their attempts or inputs the correct answer.

So long story short, the password input is inside the loop so the user has chances to continue to input their password until they get it right (or run out of attempts).

Hope this helps!

Yes! This is very helpful. Thank you for the detailed explanation.