Esperanto is the most commonly used artificial language. It was created by Polish physician Ludwig L. Zamenhoff and was first presented in 1887. The name of the language comes from the pseudonym ("Doktoro Esperanto") used by the author in his first textbook.
Esperanto can be learned considerably quicker than a typical natural language. The grammar is extremely regular, yet not primitive. There is only one paradigm for nouns and one paradigm for verbs. There is a simple relation between written and spoken text. The word order is "free", allowing topic-focus articulation.
About 70% of Esperanto vocabulary come from Romance languages, about 20% from Germanic languages and English and some part from Slavic languages. The word-building is very rich and highly regular.
The most of the estimated numbers of Esperanto speakers range from 1 to 10 millions. There are about 1000 native speakers (either parents had different native language and used Esperanto as the common language, or bilinguals). Several tens of thousands of books have been published in Esperanto (original and translated), and there are many periodicals.
There are two tendencies in the current Esperanto (as in any other language) - conservative and progressive. The conservative group uses as a measure of the correctness of the language the books written by Zamenhof, mostly ones collected in the so called Fundamento. According to them, these things are untouchable (even Zamenhof's mistakes :)). There is a second group trying to change the language to make it more international, more close to English, easier to use etc. Some of the proposals are unsuccessful, some are partially used and some are even made official by Akademio - the headquarter of the Esperanto world. There is a third group of Esperanto users - AIL, group of scientists that uses the language for pragmatic reasons and wants to distinguish itself from the former two groups. They call the language ILO - Internacia Lingvo (International language), the original name used by Zamenhof.
My master thesis was about Esperanto morphology and it's analysis by a two-level system, see bibliography (in English, contains grammar overview).
Here are some reasons for doing that: