How does the Internet work? ： https://developer.mozilla.org/en-US/docs/Learn/Common_questions/How_does_the_Internet_work
How the Web works ： https://developer.mozilla.org/en-US/docs/Learn/Getting_started_with_the_web/How_the_Web_works
What is a web server? ： https://developer.mozilla.org/en-US/docs/Learn/Common_questions/What_is_a_web_server
HTTP Response Codes ： https://dev.opera.com/articles/http-response-codes/
HTTP methods : OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, CONNECT