The rapid growth of the World Wide Web has caused serious performance degradation on the Internet. This paper o ers an end-to-end approach to improving Web performance by collectively examining the Web components clients, proxies, servers, and the network. Our goal is to reduce userperceived latency and the number of TCP connections, improve cache coherency and cache replacement, and enable prefetching of resources that are likely to be accessed in the near future. In our scheme, server response messages include piggybacked information customized to the requesting proxy. Our enhancement to the existing request-response protocol does not require per-proxy state at a server, and a very small amount of transient per-server state at the proxy,