Ludwig Lazarus Zamenhof (pronounced /ˈzɑːmɨnhɒf/ in English; born Leyzer Leyvi Zamengov) (December 15, 1859 – April 14, 1917) was the inventor of Esperanto, the most successful constructed language designed for international communication.
Zamenhof was born on December 15 (December 3 OS), 1859 in the town of Białystok in the Russian Empire (now part of Poland). He considered his native language to be his father's Russian (or perhaps Belarusian, which was not considered distinct from Russian at the time and which appears to have had a strong influence on Esperanto phonology), but he also spoke his mother's Yiddish natively; as he grew older, he spoke more Polish, and that became the native language of his children. His father was a teacher of German, and he also spoke that language fluently, though not as comfortably as Yiddish. Later he learned French, Latin, Greek, Hebrew, and English, and had an interest in Italian, Spanish and Lithuanian.
In addition to the Yiddish-speaking Jewish majority, the population of Białystok was made up of three other ethnic groups: Poles, Germans, and Belarusians. Zamenhof was saddened and frustrated by the many quarrels between these groups. He supposed that the main reason for the hate and prejudice lay in mutual misunderstanding, caused by the lack of one common language that would play the role of a neutral communication tool between people of different ethnic and linguistic backgrounds.