There’s a lot to yoga. Way more than touching your toes and standing on your head. It’s a science, a philosophy, a way to live. If you’re ready for some yoga self-education, read some (or all!) of these well written books:
Yoga: The Greater Tradition by David Frawley
This book is short, easy to read, and does a great job of introducing the philosophy of yoga and its spiritual side.
The Complete Illustrated Book of Yoga by Swami Vishnu-devananda
Delving a little deeper, Swami Vishnu-devananda explains the physical effects of yoga from a scientific perspective and how all this relates to the mind and spirit. The book has nearly 150 photos of classical hatha yoga asanas and directions for their practice (which are great for reference, but must be properly learned from a teacher).
Hatha Yoga Pradipika by Swami Muktibodhananda
Now we’re going really deep. This is one of the ancient yogic texts with verses translated from Sanskrit. It’s good for those who already have a strong grasp on yogic philosophy, and it’s a book that will guide you through your entire yogic journey (aka your whole life!)
Living Yoga by Georg Feuerstein and Stephan Bodian
A good book for beginners and those entirely new to yogic philosophy, Living Yoga gives a very broad overview of the many paths of yoga.