When most people think about a book for children, they think about picture books. The audience of picture books is children that go to nursery school and elementary school.
Picture books usually have somewhere between 150 and 1,000 words. In such books, it is the illustrations that have to attract interest and convey the meaning. It often happens that writers of picture books can’t create illustrations. Publishers of picture books will often match up illustrators with writers. Even if they can’t create illustrations, authors of picture books need to think about how their words will transform into drawing and how a compelling story consisting of words and pictures would look like.
Even though they are aimed at children, picture books need to have stories, because children do enjoy following one or two characters through a simple line of events that they can relate to, such as a day playing games, a birthday party and so on.
While some children may not be able to read the words yet, they will recognize the words when someone is reading their favorite book to them. Later on, they will be able to read for themselves.