Atomic Habits by James Clear explains how small, seemingly insignificant changes in behavior can have a significant impact over time. The source emphasizes that building good habits involves understanding the four stages of habit formation: cue, craving, response, and reward. It then delves into strategies for making habits more appealing, such as temptation bundling, where a desirable activity is linked to a less enjoyable but important one. The source further explores the importance of reducing friction by simplifying the process and applying the two-minute rule, making it easier to start new habits. Finally, it highlights the significance of habit tracking and using habit contracts to increase accountability, and suggests using habit stacking to build new habits by linking them to existing ones.