This essay provides a comprehensive discussion of four key strategy development tools: PESTLE analysis, Porter's Five Forces model, SWOT analysis, and Input/Output analysis. The essay explains the components and applications of each tool, demonstrating how companies utilize them to assess external factors, evaluate competitive positions, analyze internal strengths and weaknesses, and understand the interdependencies within the economy. The essay includes practical examples, such as Nike and Coca-Cola, to illustrate the real-world application of these strategic models. It concludes with a discussion of how businesses can apply these tools to make informed decisions, develop strategic plans, and achieve competitive advantage. The essay adheres to the guidelines of the HI6006 Competitive Strategy course, including appropriate formatting and Harvard referencing style.