What is Esperanto?
There is a lot of information on the internet about Esperanto - - what kind of language it is, what are its objectives, what kinds of materiais for acquiring it are available. One of the best maintained is at esperanto.net. Here is a link to its English language edition.
The late Donald Harlow was one of the first to compile a comprehensive set of internet materials on Esperanto. He included a wider range of details than you might expect, e.g. on constructed languages and the opinions of some twentieth century governments. He also gave practical suggestions on how you might use Esperanto and where you could find more information via the net in many countries across the world. Much of his work has been retained on the internet as a mark of admiration as well as respect.
A condensed, but highly technical answer to the above question is offered by Ed Robertson on the Scottish Esperanto Association's website. Professional inquirers are directed to further reading, including the book by Christopher Gledhill, "The Grammar of Esperanto: A corpus-based description" (2nd edition), München: Lincom, 2000
The world has a serious language problem. We have a solution which is easy, useful, and most importantly, fair" So opens a short but exemplified account from the British Esperanto Association.