Books come in different sizes, just like toys or clothes. Sometimes a book can be small, like one that can fit in your pocket. Other times, it can be bigger, like one that is as big as a grown-up's hand. The size of a book can depend on the story it tells, how many pictures or words are in it, or just what the author or publisher likes.
The size of a book can also help you figure out how to read it. If a book is really big, you might need to hold it with two hands or rest it on a table. If it's small, you might be able to carry it around with you wherever you go. So, just like in life, it's important to find the right book size that works for you!