What was Peter Pan before it a became book?

Peter Pan wasn't a book before it became a book! It was originally a play called "Peter Pan, or The Boy Who Wouldn't Grow Up" written by J.M. Barrie.

The play premiered in London in 1904 and was a huge success. Barrie later adapted the play into a novel called "Peter and Wendy" in 1911. So, the play came first, then the book!