If you are interested in some brief information about the nature of Esperanto, go here.
Esperanto has been represented on the internet for at least as long as the internet has been public. While I personally have not been here that long, I know that Neal McBURNETT's Esperanto-English vocabulary was made available by FTP in the early 1980s. The newsgroup soc.culture.esperanto and its companion Esperanto mailing list date from late in the 1980s. Today they have been joined by a very large number of other Esperanto sources and services on-line.
Here are a few things you should know about using Esperanto on-line.
Like most languages, Esperanto's alphabet has several characters not included in the alphabet used by English. Unfortunately, the standard set of letters for use on-line was defined by American engineers, who were not particularly aware of, or interested in, the problems faced by users of other languages.
As the net becomes global in nature, solutions to this problem are gradually coming into effect. Esperanto, like many other languages, is included in the Unicode standard which is becoming dominant in certain parts of the net (notable, web pages created in non-English-speaking countries); those using recent versions of Windows (late versions of 95 and later) will automatically have Unicode fonts with Esperanto characters in their machines. In the meantime, workarounds are being used, currently mainly for newsgroup postings and e-mail. The two main ones:
(1) Esperanto and numerous other languages have taken to using extra letters or symbols to show the presence of diacritics or (in the case of Chinese) tones. The most common system is to place a letter 'x' after the Esperanto letter that should carry a supersign; this is permissible and desirable because 'x' is not a letter of the Esperanto alphabet, and so no confusion will arise. Two other relatively common systems are to place a caret '^' either before or after the letter; the former has the advantage that it is the same usage as we find in the TeX typesetting language. There is also a commonly used system in which the supersigned letters are indicated by a following 'h', except for the supersigned 'u', which is simply shown without a supersign; this has the disadvantage that it removes phoneticity from the language's alphabet, but has the advantage that it is traditional (having been defined at least as early as 1905, in the Fundamento de Esperanto).
(2) The International Standards Organisation has established a series of norms for the use of bytes 128 through 255 for non-English characters. There are some ten of these additional character sets now in existence. Esperanto characters are to be found in ISO 8859-3. You can find, and download, fonts that will handle text written in this format via this site.
If you speak English, but not Esperanto, you will want to access the parent page at this site.
Se vi parolas Esperanton, sed ne la anglan, vi prefere iru al la Virtuala Esperanto-Biblioteko, kiun administras Martin WEICHERT.
If you speak both languages, you may choose either of the above sites. The Virtuala Esperanto-Biblioteko, a cooperative effort, is perhaps more complete.
You can find information about how to learn Esperanto here.
If you are a beginner and feel that you would like to join a list with other beginners, there is an English beginners' mailing list available. Another such list, not restricted to English speakers, can be found in Yahoo Groups. There is also a UseNet newsgroup for Esperanto beginners.
Lists of on-line magazines in Esperanto can be accessed here or here.
Reading material in Esperanto is available on-line here.
If you'd like to correspond with someone in Esperanto, go here or here.
If you'd like to hear Esperanto spoken, check out the Esperanto radio archive (Real Audio 2.0 or better required). With RealAudio, you can read Esperanto and hear it spoken simultaneously here. Ditto for MP3 here.
If you are interested in participating in large-scale events where Esperanto is spoken, you can find a list of those with Web pages here and a much more complete list, including many not advertised on-line, here.
If you'd like to participate in an on-line forum in Esperanto, the best is here. Other less-used Esperanto newsgroups can be found here, here, and here.
2007.12.16: Esperanto-Nepali Dictionary, PDF format. Added here.
2007.12.16: Nepali-Esperanto Dictionary, PDF format. Added here.
2007.11.29: 24th Springtime International Week, Waldfischbach-Burgalben, Germany, Mar. 21 - 28, 2008. Added here.
2007.11.18: Esperantists of New Jersey. Added here.