Esperanto is the most widely spoken constructed international auxiliary language in the world. Its name derives from Doktoro Esperanto, the pseudonym under which L. L. Zamenhof published the first book detailing Esperanto, the Unua Libro, in 1887. The word esperanto means 'one who hopes' in the language itself. Zamenhof's goal was to create an easy and flexible language that would serve as a universal second language to foster peace and international understanding.
Esperanto has had continuous usage for over a century by a community now estimated at about 2 million speakers, and approximately one thousand native speakers. However, no country has adopted the language officially. Today, Esperanto is employed in world travel, correspondence, cultural exchange, conventions, literature, language instruction, television, and radio broadcasting. Also, there is an Esperanto Wikipedia with about 231,000 articles (as of July 24, 2016).
There is evidence that learning Esperanto may provide a good foundation for learning languages in general. Some state education systems offer basic instruction and elective courses in Esperanto. Esperanto is also the language of instruction in one university, the Akademio Internacia de la Sciencoj in San Marino.
Free on-line courses to teach the international language are available through lernu.net and duolingo.com. The first of these sites has over 223,000 registered users, who are able to view the site's interface in their choice of 18 languages. About 46,800 of the lernu.net users possess a basic, intermediate or advanced understanding of Esperanto. On March 25, 2016, when the Duolingo Esperanto course completed its beta-testing phase, that course had 350,000 people registered to learn Esperanto through the medium of English; in the subsequent four months, the number of learners has increased to 466,000. Duolingo contributors are also preparing an Esperanto course intended for speakers of Spanish, expected to be released to beta testing during the summer of 2016.