Duolingo uses several gamification techniques to keep users engaged and motivated. Here are the main ones:

• Gems/lingots: These are virtual currencies earned by completing lessons and daily quests. They can be spent in the app's shop. This system motivates users by rewarding their efforts and giving them something to strive for.
• Streaks: Streaks count how many consecutive days users complete lessons. This creates a habit of daily learning. Features like the "weekend amulet" and "streak freeze" help users maintain their streaks even if they miss a day or two, which keeps them from losing motivation.
• Experience points (XP): XP shows progress and mastery of the language. Setting daily XP goals encourages consistent practice. It gives users immediate feedback and a sense of accomplishment.
• Leaderboards: Users earn points for completing courses, and these points put them on a leaderboard. This creates a sense of competition and community. However, some users might find the competition discouraging if they can't keep up.
• Achievement badges: Badges are rewards for reaching milestones and are displayed on user profiles. They give a sense of recognition and motivate users to keep learning to earn more badges.