There are courses in the following languages: English, French, German, Hindi, Icelandic, Italian, Japanese, Mandarin Chinese, Portuguese (Brazil), Russian, and Spanish. Usually there are four courses per languages: 101, 102, 201, 202. These courses are divided into several Units, which include from 4 to 6 Lessons. The lessons are: Learn, Reading, Listening, Magnet, Writing, and Speaking. The lessons each focus on different aspects of learning the material in that lesson. The first four kinds are mainly drills for practicing. Then the Writing and Speaking lessons are more interactive: you either write some sentences based on the instructions, or record yourself speaking a paragraph, then native speakers in the language can give you criticisms and rate your performance.
There is an experience-points system that can be motivating for some people. You receive points for doing various things like commenting on someone's Writing or Speaking exercises (bonus points for being the first to comment), for doing the lessons, for chatting for over 5 minutes, for doing translations, for creating flashcard sets... You get little awards, and you see the awards that your friends get. For example, after 1000 points you get a bronze medal, 5000 is a silver, and 10000 is a gold; you also get more immediate awards like "Teacher of the week in English" or "Top 100 student in Mandarin Chinese".
The site is very web 2.0, socially-oriented. You can add friends, which are suggested to you based on your personal information such as native language, the languages you're learning, age, reasons for learning, etc.. You can also chat live with people either by typing or using a microphone, and you can leave and read messages.!