HTTP

How does HTTP work?

The best resource I found is this Quora answer to How does HTTP work?. In summary, when you input a URL into your browser's location bar and press enter, this is typically and loosely what happens:

• Using DNS, the URL is resolved into an IP address.

• A TCP connection is established with the web server answering at that IP address. Alternatively, a TLS-encrypted TCP connection is established if using HTTPS.

• HTTP messages are exchanged, the browser sends requests and the server sends back responses. It starts with a GET request for the document referenced by the URL but many more request/response pairs are exchanged to load all of the different resources that make up a particular web page.

References

• HTTP on MDN

How do browsers render web pages?

• Tali Garsiel and Paul Irish's famous How Browswers Work give some details about the way browsers process the HTTP responses to render a particular web page.

• The video How do web browsers work? | Web Demystified, Episode 5 is an easy watch and gives a nice overview.

Exercises

• Add details of the HTTP request methods to your spaced repetition system.

• Build a low level library that is able to compose and send HTTP requests and spit out HTTP responses.