The document analyzes the total cost of ownership (TCO) of web applications in the cloud versus on-premises data centers, demonstrating that Amazon Web Services (AWS) can offer substantial cost savings—up to 80%—under various usage scenarios. It outlines AWS's pricing philosophy, including pay-as-you-go and reserved instance options, which provide flexible pricing strategies tailored to different consumption patterns. Through three representative web application scenarios, the paper highlights the financial advantages of using AWS while emphasizing the importance of understanding usage patterns to maximize cost savings.