Multiple entities in the smartphone ecosystem employ various methods to provide better web browsing experience. In this paper, we take a first comprehensive examination of the resource usage of mobile web browsing by focusing on two important types of resources: bandwidth and energy. Using a novel traffic collection and analysis tool, we examine a wide spectrum of important factors including protocol overhead, TCP connection management, web page content, traffic timing dynamics, caching efficiency, and compression usage, for the most popular 500 websites. Our findings suggest that that all above factors at different layers can affect resource utilization for web browsing, as they often poorly interact with the underlying cellular networks. Based on our findings, we developed novel recommendations and detailed best practice suggestions for mobile web content, browser, network protocol, and smartphone OS design, to make mobile web browsing more resource efficient.