This report provides a critical evaluation of business-to-business (B2B) relationships, focusing on their impact on supply chain management and overall business performance. The report begins by defining B2B relationships and contrasting them with B2C and B2G transactions. It highlights the importance of B2B for an organization's sustainability and its role in improving the supply chain process. The report uses the example of a Thai T-shirt factory to illustrate how supply chain management, including elements like employees, buyers, sellers, and raw materials, contributes to the production and quality of the final product. It emphasizes how improvements in the supply chain can help a company like the T-shirt factory expand its operations and enhance customer satisfaction. The report references academic sources, including journals and online resources, to support its analysis and findings.