This report provides a comprehensive analysis of different types and sizes of business firms, focusing on the UK-based multinational company Marks and Spencer (M&S). It begins by defining and differentiating between micro, small, medium, and large businesses, outlining their key characteristics and providing examples of competitors within the retail sector. The report then delves into various company structures, including sole traders, partnerships, limited liability companies (LLCs), public limited companies (PLCs), and cooperatives, explaining their features and providing real-world examples. Furthermore, the report explores different organizational structures, such as divisional and functional structures, and assesses their impact on employee productivity. Finally, it utilizes PESTLE analysis to examine the external factors—political, economic, social, technological, legal, and environmental—that influence business performance, with specific examples related to M&S. The report concludes by summarizing the key findings and insights into the dynamics of the business environment.