The Brief: Duolingo is a free language-learning app.
DEEP DIVE
Users complete short, game-like lessons, ascending to higher levels of comprehension and speaking. Duolingo has courses in over 30 international languages including Klingon. Over 300 people have signed up for Duolingo.
Duolingo Plus is a paid service within the app that makes Duolingo ad-free and allows for offline use.