Focusing more on the illustrations than the text, picture books need the visuals to have a story. Due to the images' important part in the storytelling, picture books are also called "picture story books." They are usually 32 pages long and are addressed to children of four to eight years old.
Intended for new and emerging readers, early readers' books help children who are starting to read on their own. Like the children's picture books, early readers' books include illustrations on every page, but the focus in this case is on the text. Aimed at children from six to eight years old, the books usually have a more grown-up look to them and there is significantly more writing on every page.
Children's picture books can vary in length, subject, size of text and physical size. Based on these factors, picture books are broken into two subcategories. Board books are picture books intended for the youngest readers. Their pages are made of thick cardboard instead of paper and they usually include very short stories with illustrations dominating the book. The concept books introduce preschoolers to basic counting, the alphabet, animals and colors. The writing is minimal and the concepts are taught to young readers mainly through images.
Shaped more like grown-up chapter books than picture books, the focus of early readers' literature shifts from images to text. The purpose of these books is to prepare and encourage children to read on their own. The length of the text varies, with some early readers' books including stories of a few sentences and other books containing more extended and complicated stories for early readers that have gained some experience in basic reading. Early readers' books can even be so advanced that they introduce children to nonfiction subjects, such as history, music, math or art. An engaging word rhythm, a repetitive vocabulary, an understandable context, and a strong picture and text connection are characteristics of all early readers' books.