Issue link: https://read.uberflip.com/i/1146286
6 Chapter B CHAPTER B HTTP Overview 2 Before diving into the specific rules for making web pages faster, it's important to understand the parts of the HyperText Transfer Protocol (HTTP) that affect perfor- mance. HTTP is how browsers and servers communicate with each other over the Internet. The HTTP specification was coordinated by the World Wide Web Consor- tium (W3C) and Internet Engineering Task Force (IETF), resulting in RFC 2616. HTTP/1.1 is the most common version today, but some browsers and servers still use HTTP/1.0. HTTP is a client/server protocol made up of requests and responses. A browser sends an HTTP request for a specific URL, and a server hosting that URL sends back an HTTP response. Like many Internet services, the protocol uses a simple, plain- text format. The types of requests are GET, POST, HEAD, PUT, DELETE, OPTIONS, and TRACE. I'm going to focus on the GET request, which is the most common. A GET request includes a URL followed by headers. The HTTP response contains a status code, headers, and a body. The following example shows the possible HTTP headers when requesting the script yahoo_2.0.0-b2.js. GET /us.js.yimg.com/lib/common/utils/2/yahoo_2.0.0-b2.js HTTP/1.1 Host: us.js2.yimg.com User-Agent: Mozilla/5.0 (...) Gecko/20061206 Firefox/1.5.0.9 HTTP/1.1 200 OK Content-Type: application/x-javascript Last-Modified: Wed, 22 Feb 2006 04:15:54 GMT Content-Length: 355 var YAHOO=...