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 by a community estimated at between 100,000 and 2 million speakers for over a century, 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 over 216,500 articles (as of July 15, 2015).
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 almost 200,000 registered users who are able to view the site's interface in their choice of 18 languages, and at least 44,000 of whom have basic, intermediate or advanced understanding of Esperanto; the latter site currently has about 57,000 people signed up to learn Esperanto through the medium of English.