The Raspberry Pi has two versions of Python installed on it: Python 2.7 and Python 3. Usually when software or programming languages are updated, the new version is compatible with the old version. Python 3 was intentionally designed not to be compatible, however, so programs written for Python 2.7 might not work with Python 3, and vice versa. In this book, we’re going to use Python 2.7, because it makes it easier to install some of the software required for the projects in Part V of the book. You can find out more about what’s different about Python 3 at
Programmers often use something called an integrated development environment (IDE), which is a set of tools for creating and testing programs. The Python IDE is called IDLE, and there are two versions of it on your desktop: IDLE (which is for Python 2.7) and IDLE 3 (which is for Python 3). Double-click the IDLE icon to get started.