I cannot praise this amazing, wonderful book enough. I bought it for my sharp, curious four-year-old daughter and she loves it, often requesting a reading from it at bedtime instead of her storybooks. It is truly a "big book of everything." It's sections cover human anatomy and physiology, animals, plants, the universe, planet earth, basic physics and chemistry, and an extensive "key facts" section in the back of the book. Although I am college educated, reading it has been like taking a refresher course, and I have learned many new things from this book. It is factually accurate, SPECTACULARLY illustrated, visually interesting, very readable, and somehow, believe it or not, excellent and useful for persons aged 4 through adult. If I could, I would buy every child a copy.