Do you remember the Pythagorean Theorem from math class?

When your Python program doesn't work as expected, it's because of a bug, or an error.

Sometimes you want to give your Python script information right when you run it from the terminal, without waiting for it to ask for input.

If you're learning to code, you'll almost certainly encounter the FizzBuzz problem.

Imagine you have a list of phone numbers, but instead of accessing them by a numeric index like 0 or 1, you want to look them up by a person's name.

What if you could solve a big problem by solving a smaller, identical version of the same problem?

So far, your programs have probably read input from the keyboard and displayed output on the screen.

What happens when your program encounters an error, like a user entering text instead of a number, or trying to open a file that doesn't exist?

As your programs get bigger, you'll find yourself repeating the same blocks of code.

A function that does the exact same thing every time is useful, but a function that can be customized each time you call it is even better.

So far, you may have used variables to store single values like a number or a string.

Python's lists are powerful, but their true flexibility comes from the built-in methods you can use to manipulate them.

It's completely normal to make mistakes when you're programming—everyone does!

What if you want your program to do different things based on different conditions?

Your code often needs to choose between more than just two options.