To kick off the site, I should first tell a little about Esperanto, the international language.
The idea of Esperanto was published by the doctor L. L. Zamenhof. His stated intention was to introduce a new primary secondary language.

And just how does this make sense, exactly?

Zamenhof explains how his home town of Bialistok was made up of several, very diverse population groups; and he felt that many of the conflicts in the area could be resolved by overcoming the language barriers. As Zamenhof was very linguistically well-equipped, he decided to look into creating an independent language in order to get around the fundamental premise of using national languages to communicate: This communication will always favor one part or the other. And if the language used is the lingua franca of the time - as many languages have been over time, and which English probably is in this day and age - it will be done on the cultural basis of that nation.
The intention with Esperanto was, then, to create a neutral language intended to be a foreign language only - and the main tool for this task. And so: A primary secondary language. It is important to stress that the intention is not to use this language to supplant the national languages - the natural languages, as they say - but to encourage the active development of these languages and let them exist independently without excessively letting the communication language influence the national languages.

To make this work, Zamenhof constructed Esperanto. Actually, he presented it in his book Unua Libro as the international language published by La Doktoro Esperanto - Esperanto for The Hoping Doctor. And he put together a language which was extremely modular and which did not have many of the irregularities that make most languages complex to understand and to learn to use. And while a lot of languages make it possible to derive other word forms from a word - such as milky from milk - Esperanto is designed to facilitate and extend this, so changing the prefix changes the word type and function.

And with this, it is probably time to put some examples on the table. I shall use skribi, to write.Esperanto uses letters from the same alphabet as the English one - with the slight difference that some of them feature a small ‘hat’ - i.e. ĝ or ŭ.
First, skribi - to write. Here, we see the stem of the word and the ending: Skrib|i. The ending -i indicates that it is a verb.
Changing the ending, we get skrib|o - skribo, writing. The -o ending thus indicates a noun.
Again, changing it to skrib|a, the -a ending indicates an adjective, so an example would be skriba papiero, writing/letter paper.
Accordingly, the ending -e indicates an adverb, so skribe would mean in writing.

To make it more interesting, a system of affixes exist - both prefixes (i.e. ek|skribi, to start writing) and suffixes (i.e. skrib|ilo, a tool for writing, or skrib|isto, a person who works with writing). Working with a long list of affixes, it is possible to style the words from their original base to great refinement.
An example of this is a nuance which is not present in a lot of languages: Rus|o means a Russian, ie. a member of the ethnic group which is Russians; Rus|ulo means a person from Russia. This could be an ethnic German, Mongol, Swede or whatever living in Russia. The Russian language has this distinction - Русские-Российские - but this is generally difficult to translate, because most languages do not feature this distinction.
Another interesting feature is that the affixes themselves have independent meaning. In the above example, it was mentioned that -ulo is a suffix indicating a person; but ulo is a word in itself, indicating a person. Similarly, I mentioned skrib|ilo as a writing tool above; but ilo can be used to indicate ‘a tool’ by itself.

Esperanto is built on a principle of being productive and reproductive - being able to interpret and construct words and sentences from a relatively small vocabulary and a limited rule set makes it quite easy to learn. It quickly becomes a functional tool without the need to figure out the quirks of most other languages. Not using several grammatical genders, not having many conjugations of verbs, using endings to clearly indicate every word’s function in the sentence regardless of the word order and other technical tools indicate the emphasis on function.

The value system around the language - the purpose of the language was, after all, to build a bridge between peoples - has been the basis for a global Esperanto movement with the green Esperanto flag featuring la Verda Stelo, the Green Star of Esperanto. While Esperanto has not caught on to the extent that many might have hoped for, it is certainly the most popular artificial language, even if the number of speakers is difficult to estimate, as discussed in the Wikipedia article on Esperanto. Suffice it to say that there are Esperanto speakers all over the world, and the language is being actively spoken and developed. Interestingly, a number of otherwise quite censoring regimes have approved of, or at least allowed the international language.
Occasionally, there has been criticism of the language and the culture around it as being an artificial construct and, as such, forced rather than grown up naturally, which is a valid point. Also, it is true that the language has distinct European roots, which may not make it seem as obvious an international language to people outside of Europe. Still, it seems quite popular in China, for instance. An often-repeated statement that the international language should be a safeguard against foreign influence in the national languages seems a bit of a stretch; but this argument is a disservice to Esperanto, which is usually a statement issued by anti-internationalists in general, who do not just fear foreign language influence, but indeed also the general ongoing development in the national language and feel that any development from the inside is a negative thing, a distortion of the original language. And that is a completely different discussion, outside the scope of the Esperanto movement.

On a personal note, I am probably an Esperantist primarily based on my linguist background. But I do find it interesting to note that the values of the language and the movement - communicating across languages and borders - lie deep in most Esperantists; and I find that despite differences in political, religious and general personal beliefs, this is a set of values that everyone should be able to embrace. I do appreciate this kind of internationalism which equally encourages the national perspective.