Duolingo

Duolingo is a language learning platform that delivers structured lessons through a mobile app and web browser. Each session typically takes 5–10 minutes and covers vocabulary, grammar, speaking, and listening within a single exercise. The app uses spaced repetition and adaptive difficulty to adjust content based on a learner's past performance. Languages are divided into skill units organized along a guided learning path, and progress is tracked through XP points, daily streaks, and weekly leaderboards that introduce a light competitive element. Duolingo is commonly used by students picking up a second language, travelers preparing basic vocabulary before a trip, and adults returning to a language they studied in school. The short lesson format fits naturally into commute routines or daily breaks. Some learners use Duolingo alongside textbooks or formal courses to maintain daily vocabulary exposure. The platform also offers Duolingo for Business, a team-facing version used by organizations supporting employee language learning. Duolingo is effective at vocabulary acquisition and forming daily language habits. A study cited by Duolingo found that 34 hours of use can produce vocabulary gains equivalent to one semester of university-level language study. That said, the platform has well-documented limitations: grammar explanations are minimal, speaking practice is limited compared to immersive methods, and the free tier restricts mistakes through a hearts system that pauses lessons. Most language educators treat Duolingo as a useful supplement rather than a standalone route to conversational fluency.