Of all the instruments that have been created over the centuries of people making music, there's been no other with the staying power of the piano. Not only are there plenty of variations on the piano itself, from the baby grand to the modern digital piano, but there are so many other instruments based on it that it would be hard to count them all: organs, keyboards and MIDI controllers, to name just a few examples. To get started with any (or all) of these diverse instruments, piano method books are step one.
If you're new to music, your first question would probably be "what's a method book?" The answer is that it's a sort of written teacher-on-a-page that can guide you through the learning process and lead you on to the next step once you've mastered a technique or theory. Even if you're taking formal lessons, practicing on your own time is the most important way to improve your skills, and piano method books can be your guide during those times. Some, like the Hal Leonard Learn & Master Piano DVD/CD/Book Pack, even include multimedia that can really help you out with visual demonstrations, accompaniments, play-along exercises and more.
One thing to consider when choosing a method book is your own skill level. Learning the piano is a lengthy process, and you'll find that there are a ton of different books aimed at specific portions of that journey. They're also tailored by age, so if you're searching for a book for your child, you might try one such as the Alfred Music for Little Mozarts Music Lesson Book 2. On the other hand, if it's for yourself, take a look at options like Faber Piano Adventures Adult Piano Adventures All-In-One Lesson book.
There are hundreds of method books in this section to choose from, so there's no doubt that you can find a perfect fit for any student at any stage of the learning process. Whether you're looking for a kids' guide to help your young musician between lessons or a self-study book to teach yourself piano in your spare time, you'll find it right here.