L. L. Zamenhof[a] (15 December 1859 – 14 April 1917)[b] was the creator of Esperanto, the most widely used constructed international auxiliary language.

He grew up fascinated by the idea of a world without war and believed that this could happen with the help of a new international auxiliary language.

[6] In light of his achievements, and his support of intercultural dialogue, UNESCO selected Zamenhof as one of its eminent personalities of 2017, on the 100th anniversary of his death.

However, as the area was a part of the Russian Empire at the time, his name was recorded on his birth certificate as Лейзер Заменгов, Leyzer Zamengov, using the Yiddish form of the forename and a russified version of his surname;[11] many later Russian language documents also include the patronymic Маркович, Markovich « son of Mark » (in reference to his father, Markus), as is the custom in the language.

While at university, Zamenhof began using the Russian name Lyudovik (also transcribed Ludovic or translated as Ludwig) in place of Lazar, possibly in honor of Francis Lodwick, who in 1652 had published an early conlang proposal.

[18][19] In addition to the Jewish Yiddish-speaking minority, the population of Białystok included Roman Catholic Poles and Eastern Orthodox Russians (mainly government officials), with smaller groups of Belarusians, Germans and other ethnicities.

He supposed that the main reason for the hate and prejudice lay in the mutual misunderstanding caused by the lack of a common language.

If such a language existed, Zamenhof postulated, it could play the role of a neutral communication tool between people of different ethnic and linguistic backgrounds.

[20][21] As a student at secondary school in Warsaw, Zamenhof attempted to create an international language with a grammar that was rich, but complex.

[24] For two years, he tried to raise funds to publish a booklet describing the language, until he received the financial help from his future wife's father.

In this work, not only does he provide a review of Yiddish grammar, but also proposes its transition to the Latin script and other orthographic innovations.

A wave of pogroms within the Russian Empire in 1882, including Congress Poland, motivated Zamenhof to take part in the Hibbat Zion, and to found a Zionist student society in Warsaw.

[27] He left the movement following the publication of Unua Libro in 1887, and in 1901 published a statement in Russian with the title Hillelism, in which he argued that the Zionist project would fail due to Jews not having a common language.

Zamenhof died in Warsaw on 14 April 1917,[b] possibly of a heart attack,[28] and was buried at the Okopowa Street Jewish Cemetery.

"[29] Zamenhof and his wife Klara Silbernik raised three children, a son, Adam, and two daughters, Zofia and Lidia.

[30] Lidia Zamenhof in particular took a keen interest in Esperanto, and as an adult became a teacher of the language, traveling through Europe and to America to teach classes in it.

[33] In 1910, Zamenhof was first nominated for the Nobel Peace Prize, by four British Members of Parliament (including James O'Grady and Philip Snowden) and Professor Stanley Lane Poole.

[35] On the occasion of the fifth Universala Kongreso de Esperanto in Barcelona, Zamenhof was made a Commander of the Order of Isabella the Catholic by King Alfonso XIII of Spain.

There are others in Poland, the United Kingdom, France, Hungary, Croatia, the Czech Republic, Spain (mostly in Catalonia), Italy, Israel, Belgium, the Netherlands and Brazil.

On 15 December 2009, Esperanto's green-starred flag flew on the Google homepage to commemorate Zamenhof's 150th birthday.