Learning foreign languages and other subjects in self-study

Esperanto

Esperanto is a planned language developed around the end of the 19th century. It has the most amount of speakers among all planned languages. There are speakers of Esperanto everywhere in the world. Particular hotspots for Esperanto are Europe, Brazil, Iran, Japan and Russia and it is not as popular in English-speaking countries, though you should still be able to find an Esperanto club in every major city. The grammar is very easy and regular and the vocabulary is taken from European languages including English. Thanks to a large and intuitive system of prefixes and suffixes, even non-Europeans can develop their vocabulary much more quickly than in other languages.

What to expect when studying Esperanto: English speakers will find that they can learn Esperanto incredibly fast, maybe 5 times faster than another European language. There are lots of free courses and many have a network of volunteers who'd correct your exercises or answer questions. However, since these courses usually aren't created by professionals and most if not all interaction will be through e-mail, you may find part of them didactically unsound and you may experience a delay in developing actual conversational fluency.

Advice for learning Esperanto: since there are very few rules in Esperanto grammar, you have to make a choice: do you want to learn all the basic rules in the course of a day or two and then spend your time reading and listening to Esperanto just to pick up vocabulary and expressions, or are you looking for a course that will introduce grammar gradually and use the time to give you a very good basis of vocabulary? Either method can work. People who already know French, German, Latin, Spanish or the like might even be able to ignore grammar completely and spend a month or two in an Esperanto chatroom in order to learn the language. Get advice valid for learning any language here.

Learn Esperanto online and for free:

Online courses:
E-mail and mail courses with tutoring in many languages
Lots of interactive, multimedia courses
Course software

Free Esperanto textbooks for self-study:
in English: Esperanto for non-grammarians
in Croatian
in Russian
in Spanish
in Swahili
in Tagalog

Be fluent in Esperanto in 3 months or less

Esperanto online dictionary

Professional (paid) translations from/to Esperanto

Information

Article: why should you learn Esperanto

Pronunciation

Beginner's grammar: 16 rules of Esperanto
Advanced reference grammar: Plena manlibro (in Esperanto)

Test your knowledge of Esperanto

Good materials for studying Esperanto offline, from Amazon:
A complete grammar of Esperanto
Beginner's Esperanto
Teach yourself Esperanto
English-Esperanto-English dictionary & phrasebook
More from Amazon...

Misc resources, particularly for intermediate and advanced students of Esperanto:
Tongue Twisters
Literature in Esperanto
Newspaper in Esperanto
Free legal mp3s and texts of Esperanto music