CHAPTER 22 Hypertext Transfer Protocol 573 <start-line> <message-headers> <empty-line> [<message-body>] [<message-trailers>] The start line text identifies the nature of the message. HTTP headers can be presented in any order at all, and they follow a <header-name>:<header-value> convention. The message body frequently carries a file (called an entity in HTTP) found more often in responses than in requests. Special headers describe the encod- ing and other characteristics of the entity. TRAILERS AND DYNAMIC WEB PAGES Web pages were originally statically defined in HTML and passed out to whoever was allowed to see them. Web pages today are sometimes still created this way, but the most sophisticated Web pages create their content dynamically, on the fly, after a user has requested it. And for reasons of efficiency, the beginning can be streamed toward the