Introduction to HTTP

HTTP (Hypertext Transfer Protocol) is the foundation of how data communicates on the web. It defines how messages are formatted and sent, and how the recepients should respond to various requests.

Basic Concepts

HTTP Requests: Made by clients (like users through web browsers) to web servers to request resources. They include methods like GET, POST, PUT, and DELETE. However, our focus in this workshop will be only GET and POST.
HTTP Responses: Returned by servers to clients in response to requests. They include a status code, headers, and a body.
Status Codes: Numeric codes that tell us the result of the request. Some important codes:
- 200 OK – Request was successful.
- 400 Bad Request – The server could not understand the request due to invalid syntax.
- 401 Unauthorized – User authentication is required and has failed or has not been provided.
- 403 Forbidden – The server understood the request, but refuses to authorize it.
- 404 Not Found – Requested resource or page was not found.
Headers: Key-value pairs sent with requests and responses that provide additional information about the request or response. For example, Content-Type:text/html; specifies the media type is text as html code.
Cookies: Small pieces of data sent from a server and stored on the client. They are used for session management and tracking.

Example HTTP Request and Response

Request:

GET /index.html HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0

Response:

HTTP/1.1 200 OK
Content-Type: text/html

<html>
  <head><title>Example</title></head>
  <body><h1>Hello, World!</h1></body>
</html>

Start the challenge!