Employee engagement has been extensively studied by businesses seeking ways to ensure employees enjoy their work and are motivated. The document discusses Ian Leslie's book "Curious" and suggests that tapping into employees' innate sense of curiosity is one of the simplest and most effective ways to do so. Curiosity thrives in a "knowledge gap" where someone has enough information to learn more but not total mastery. Providing both short-term puzzles and long-term mysteries in daily tasks can fully engage employees for a long time by fueling their curiosity. Engaged employees innovate, invest in the company, and contribute to its success.