The preface is that part at the beginning of a book that you skip over to get to the good stuff, right? Sure, you can skip over it if you want (hey, you’re the one turning the pages), but who knows what you might miss. . . . It’s not very long, so maybe you should give it a look, just in case.

What is programming?

Very simply, programming means telling a computer to do something. Computers are dumb machines. They don’t know how to do anything. You have to tell them everything, and you have to get all the details right.

But if you give them the right instructions, they can do many wonderful and amazing things.

A computer program is made up of a number of instructions. Computers do all the great things they do today because a lot of smart programmers wrote programs or software to tell them how. Software just means a program or collection of programs that run on your computer, or sometimes on another computer yours is connected to, like a web server.

Python—a language for us and the computer

All computers use binary inside. But most people don’t speak binary very well. We need an easier way to tell the computer what we want it to do. So people invented programming languages. A computer programming language lets us write things in a way we can understand, and then translates that into binary for the computer to use.

There are many different programming languages. This book will teach you how to use one of those languages—one called Python—to tell the computer what to do.

Why learn programming?

Even if you don’t become a professional programmer (most people don’t), there are lots of reasons to learn programming:

• The most important is because you want to! Programming can be very interesting and rewarding, as a hobby or a profession.
• If you’re interested in computers and want to know more about how they work and how you can make them do what you want, that’s a good reason to learn about programming.
• Maybe you want to make your own games, or maybe you can’t find a program that does exactly what you want or need it to do, so you want to write your own.
• Computers are everywhere these days, so there’s a good chance you’ll use computers at work, at school, or at home—probably all three. Learning about programming will help you understand computers better in general.

Why Python?

With all the programming languages to choose from (and there are a lot!), why did I pick Python for a programming book for kids? Here are a few reasons:

• Python was created from the start to be easy to learn. Python programs are about the easiest to read, write, and understand of any computer language I have seen.
• Python is free. You can download Python—and many, many fun and useful programs written in Python—for free. I’ll tell you where in chapter 1.
• Python is open source software. Part of what open source means is that any user can extend Python (create things that let you do more with Python, or do the same things more easily). Many people have done this, and there is a large collection of free Python stuff that you can download.
• Python isn’t a toy. Although it’s very good for learning programming, it’s also used by thousands of professionals around the world every day, including programmers at institutions like NASA and Google. So once you learn Python, you don’t have to switch to a “real” language to make “real” programs. You can do a lot with Python.
• Python runs on different kinds of computers. Python is available for Windows PCs, Macs, and computers running Linux. Most of the time, the same Python program that works on your Windows PC at home will work on the Mac at your school. You can use this book with virtually any computer that has Python. (And remember, if the computer you want to use doesn’t have Python, you can get it for free.)
• I like Python. I enjoy learning it and using it, and I think you will, too.

The fun stuff

There’s just one other thing I need to mention now. . . .

For kids especially, one of the most fun parts of using a computer is playing games, with graphics and sound. We’re going to learn how to make our own games and do lots of things with graphics and sound as we go along. Here are pictures of some of the programs we’ll be making:

But I think (as least I hope) you'll find learning the basics and writing your first programs as enjoyable and rewarding as making those spaceships or skiers zoom around the screen.

Have fun!