Duolingo offers English lessons. As of early 2015, English lessons are available to Greek, Italian, Czech, Spanish, Russian, Turkish, Polish, French, Hungarian, Japanese, Ukrainian, Vietnamese, Arabic, Indonesian, Mandarin, Portuguese, Romanian, Dutch, German, Hindi, and Korean speakers.
Users of Duolingo can choose to learn more than one language. People who have previous experience with a language can take a test to advance more quickly within the course. Users earn points and reach new levels as they improve their language skills. Anyone can learn languages for free on Duolingo, and the lessons can be conducted through either the web version or the app version.