You finish a great book, feel changed by it, and a month later, you cannot name three things from it. Kern fixes that. Add a book by title and it creates a small deck of recall cards. Non-fiction gets the core ideas. Fiction gets characters, turns, and the moments that mattered. No highlights, no note exports, no writing cards yourself. Reviews come back on a spaced schedule timed to catch each one right before you forget it. Works for paper and library books. No streaks. Two books are free.