We explain the famous Fogg Behaviour Model (FBM), a framework for understanding and influencing behaviour change. Several sources detail the model's core components—motivation, ability, and prompts—and their interplay in achieving desired actions. Applications across diverse fields are examined, including marketing, website design, and public health interventions, with case studies illustrating successful implementation and challenges encountered. A key focus is on optimising for ease of action ("ability") alongside motivational strategies, rather than relying solely on high motivation.