HTTP overview of the HTTP protocol

1. Overview:
   1. Concept: Hypertext Transfer Protocol, which specifies the rules for communication between browsers and web servers
   2. Request Protocol: Client sends to server
   3. Response protocol: the server sends to the client
2. Features:
   1. HTTP is called Hypertext Transfer Protocol and is based on request/response model
   2. HTTP is a stateless protocol
      1. Stateless protocol: The HTTP protocol does not have the ability to save previously sent requests or responses
3. URL: Uniform Resource Locator
   1. Example: protocol name://domain name://port/path
   2. For example: http://www.oldboy.cn:80/index.html