This case study examines Zappos.com, a leading online retailer, focusing on its sustainable competitive advantage within the competitive landscape. The study delves into Zappos's unique business model, emphasizing its customer-centric approach and exceptional customer service as key differentiators. It explores the company's history, from its inception to its acquisition by Amazon, highlighting its financial success and the impact of its corporate culture. The analysis identifies Zappos's sources of competitive advantage, including its 24/7 call center, free and rapid delivery, and attractive product offerings. The study also discusses Zappos's commitment to core values, such as delivering 'WOW' customer experiences and fostering a positive team environment. The conclusion emphasizes Zappos's significant role in internet retailing and its commitment to customer satisfaction.