Actually a human being is treated as children from the age zero to eighteen. So different kinds of books are chosen by the children in different ages. In age zero children like picture books. This type of books can give so much amusement and learning to the children. These children books are for the ages of zero to five. Watching many pictures which can be related to many things, they will be able to know different things.
On the contrary early reader’s books are eligible for the children whose ages are in between five to seven. In that time they are eager to know about the mother tongue very finely. These children books are often designed to help a child build his or her reading skills.
Chapter related children's books are appropriate for the children whose ages are in between seven to eleven. Short chapter books are appropriate for children age’s seven to nine. In addition longer chapter books are appropriate for those children whose ages are in between nine to twelve. In another way, young-adult fiction appropriate for children age thirteen to eighteen.
Actually the criteria for these divisions are just as unclear and difficult as the criteria for defining children's books as a whole. One obvious distinction is that books for younger children tend to contain illustrations, but picture books which feature art as an integral part of the overall work also crosses genres and age levels.
Sometimes series books treated as good friend for the children. World is changing day by day and the demand for children books are also changing. It is also dependent on the willingness of a children's books writer. Book series are not same as literature.
Series books are also very popular in science fiction and crime fiction. These related books are totally dependent on the writer. As this book can be divided in many parts, children have to wait for the next part of the book. Children can not give up reading these books because it has a good relation among the parts of the books.
Series children books can live longer than its author. Say the author of a series book is died the publisher of that respective book hired another author to complete the series. Moreover children books which are treated as series books are also dependent on the popularity of that book.