Ludwig Lazarus Zamenhof was a Polish ophthalmologist and linguist, best known for creating the international auxiliary language Esperanto. Born on December 15, 1859, in Białystok, Poland, Zamenhof aimed to promote peace and understanding among people of different languages and cultures through his language. Zamenhof published the first book on Esperanto in 1887, which included grammar rules and vocabulary. His vision was to foster communication and reduce conflict caused by language barriers. Zamenhof's work has had a lasting impact, and Esperanto is still spoken by a global community today.