"Who Moved My Cheese?" is a motivational business fable written by Spencer Johnson. The story features four characters: two mice named Sniff and Scurry, and two little people, Hem and Haw, who live in a maze and search for cheese, a metaphor for happiness and success. When their cheese supply runs out, each character reacts differently to the change. The narrative illustrates the importance of adapting to change and overcoming fear. Sniff and Scurry quickly move on to find new cheese, while Hem resists change, and Haw learns to embrace it. The book encourages readers to anticipate change and take proactive steps in their lives.