The Transtheoretical Model (TTM) is a psychological framework that outlines the stages individuals go through when changing a behavior. Developed by James Prochaska and Carlo DiClemente, it identifies five key stages: Precontemplation, Contemplation, Preparation, Action, and Maintenance. This model helps in understanding how people progress through these stages and the processes involved in making lasting changes. TTM emphasizes that behavior change is not linear; individuals may move back and forth between stages. It also highlights the importance of self-efficacy and the role of external factors in influencing behavior change. This model is widely used in health promotion and addiction treatment.