Key takeaways
- HTTP is a stateless request and response protocol, which is why sessions need cookies or tokens.
- Methods, status codes and headers carry the meaning, not the body alone.
- Understanding status codes is the fastest way to debug most web problems.
The HTTP (Hypertext Transfer Protocol) is an application protocol designed to enable communications between clients and servers, and the foundation of data communication for the World Wide Web.
HTTP provide a standard way of communication between client (browsers) and web servers.
HTTP works as a request-response protocol, the web browser may be the client, and an application on a computer that hosts a web site may be the server.
For example when the client (browser) submits an HTTP request to the server, the server returns a response to the client with additional information.
HTTP is a stateless protocol because each command is executed independently of the previous commands.
From the browser, in order to access a URL you have to add the http:// command before the URL address (http://www.example.com). These days you can skip it, and the browsers will add it for you automatically when you enter an address in the URL bar.
If you want to access from the browser a HTTPS URL (Hypertext Transfer Protocol over Secure) you have to specify it manually.
Frequently Asked Questions
What is HTTP?
A stateless request and response protocol between clients and servers. Stateless is the important word: the server does not remember previous requests on its own.
If it is stateless, how do sessions work?
Through cookies or tokens sent with each request. The continuity you experience as a logged-in session is reconstructed every time from what the client sends.
What is the fastest way to debug a web problem?
Read the status code. Methods, status codes and headers carry most of the meaning, and the code usually tells you which side of the exchange to investigate.
