Book excerpt: In Web Caching and Replication, two AT&T Labs experts bring together real-world implementations, the latest IETF and W3C technical standards, and the field's most advanced research, offering systematic guidance for maximizing Web scalability and performance. The authors first introduce key concepts of Web caching and replication.They introduce HTTP's support for caching and replication, and broadly characterize Web behavior, offering practical rules of thumb for optimizing performance. Next, they focus on caching, helping implementers realistically assess proxy caching, deploy proxies in corporate and ISP networks; and utilize cooperative proxy caching. They offer in-depth insights into cache consistency, and caching the "uncacheable" -- including "cookied" and dynamic content. Part III introduces today's best techniques for web replication, offering in-depth coverage of content delivery networks, server selection, content placement, and more. For all networking professionals, IT professionals, and engineers involved with building or optimizing Internet services or equipment; for content delivery specialists and service providers; and for owners of large sites concerned about scalability and performance.