In this podcast episode, we explore the impressive success story behind Duolingo's Streaks feature, an intuitive daily lesson tracker that has played a crucial role in propelling the company's valuation to $14 billion. Host Jackson Shuttleworth, Duolingo's Group Product Manager, shares insights from over 600 A/B tests performed on this feature. These tests emphasize the value of iterative development, particularly focusing on the initial 0-7 day user experience. The conversation highlights the importance of clear communication, the option for users to pause their streaks, and finding the right balance between rewarding users for achieving perfect streaks while also allowing some leniency. Additionally, the episode emphasizes Duolingo's unique advantage of tapping into people's natural desire to learn and the significance of a strong, metrics-driven team approach to effective experimentation.