Most widely spoken of the artificial languages. L. L. Zamenhof completed the creation of the initial version in 1887. His intention was to create a language that is very easy to learn, to serve as the universal second language for everyone in the world (not, as is widely supposed, to replace all existing languages in the world).
Esperanto is an agglutinative language. It has no grammatical genders, although it does assume the male gender for many of its nouns, forcing the use of a special affix to refer a noun to the female equivalent (thus, in Esperanto, a sister is defined as a "female brother"; this male bias as served as the source of criticism of Esperanto). The language has no distinct verb conjugations by person and number, and thus no agreement between noun and verb are necessary in sentences. However, nouns and adjectives have somewhat more grammatical complexity, with two cases, nominative and accusative, and nouns and adjectives must agree in gender and number. The accusative case is also used for certain miscellaneous grammatical constructions.
The vocabulary is drawn from many European languages, chiefly English, German and the Romance languages, with a few words from Slavic languages, Latin and Greek. Zamenhof's intention had been creating a world language to linguistically unite the Jewish diaspora. To him the Yiddish language, as an old German dialect, didn't seem appropriate for this task, while old Hebrew and Latin were too difficult for a new world language. Spelling is phonetic, although this fact is complicated by the invention of new letters that are not found on any existing keyboard, and the morphology is fairly regular and in many cases easy to learn.
Esperanto has proven to be a good deal easier to learn as a second language than any of the natural languages (and, of course, much easier to learn than highly irregular and/or non-phonetic languages such as English, French, and Chinese). There is also evidence that studying an international language such as Esperanto before studying any other second language speeds and improves learning, because learning subsequent foreign languages is easier than learning one's first, while the use of a grammatically simple auxiliary language lessens the "first foreign language" learning hurdle. In one study, a group of high school students studied Esperanto for six months, then French for a year and a half, and ended up with a better command of French than the control group, who studied only French during those two years.
According to a survey by Professor Culbert of the University of Washington, about two million people speak Esperanto to Foreign Service Level 3 ability. This number is limited to those "professionally proficient" (possessing the ability to actually communicate, not just grunt greetings) in Esperanto. This survey wasn't just for speakers of Esperanto, but was a world-wide survey of who speaks what languages. This number also appears in the Almanac World Book of Facts.
Esperanto is often used to read thousands of books from an international culture. The library of the British Esperanto Association has 30,000 books in Esperanto (originals and translations) and there are also over 100 periodicals regularly distributed around the globe. Also, many Esperanto speakers use the language for free travel throughout the world using the Pasporta Servo. Still others like the idea of having penpals in about every country in the world using the Koresponda Servo.
esperi To hope esperas Am, are, is hoping esperis Was, were hoping esperos Will be hoping esperu Hope! (imperative) esperus Were to hope, would hope (subjunctive and conditional)
esperanta(n) Hoping - nominative (accusative) adjective esperantaj(n) Hoping - nominative (accusative) adjective, plural esperanto(n) Hoper - nominative (accusative) noun esperantoj(n) Hopers - nominative (accusative) noun
The -ant- infix in the above examples indicates present active participle. Participles, like tenses (above) use the vowels i, a and o to indicate past, present and future time, respectively. Example: esperinto=former hoper. Passive participles are formed like active participle, except the n is omitted (infixes -it-, -at-, -ot-). Esperanto infixes are not only used for grammatical inflections such as conjugations and declensions.
esperantino Hoper, female Esperantujo Land of hopers esperantistaro Assembly of esperantists (esperanto speakers) esperatulo Hoped-for person
There is also another language, Ido, based on Esperanto that enjoyed a period of popularity in the early 1900's, and which still has speakers today.
Also, the Esperanto Wikipedia has just started up!