John Newbery was the first printer to see a market for children's books that both instructed and amused children, so he invented the genre. His first book of this kind, A Little Pretty
Pocket-Book: Intended for the Instruction and Amusement of Little Master Tommy and Pretty Miss Polly was published in 1744, and is considered a landmark in children's literature.
Interestingly, no copy of the first edition has been found.