Lecture on HTTP: HyperText Transfer Protocol

Overview

• HTTP is the standard web protocol used to transfer hypertext and hypermedia (e.g., images).
• It is stateless, meaning each request is independent and does not retain information about previous requests.
• All data in HTTP is sent in clear text, including sensitive information like passwords.

HTTP vs HTTPS

• HTTP: Regular protocol; everything is in clear text, posing security risks, especially on public WiFi.
• HTTPS: Secure version of HTTP that encrypts the data; recommended to protect sensitive data.

HTTP Requests

• Requests are made by a client to a server to retrieve or send data.
• Example of a basic request: GET /wiki HTTP/1.1 Host: wikipedia.org
• Common tools for making requests: web browsers, apps, and software like Postman.

Network Tools

• Browsers like Firefox and Chrome have developer tools to inspect network activity (HTTP requests and responses).
• HTTP requests are ubiquitous and can be observed in network tools.

Components of HTTP Requests

• Methods: GET, POST, PUT, PATCH, DELETE, etc., each serving different purposes.
• Target: URL specifying the desired resource.
• Protocol Version: Commonly HTTP/1.1, sometimes HTTP/2.
• Headers: Additional metadata, such as expected response type and client information.
• Request Body: Contains data for requests like form submissions.

HTTP Responses

• A response from the server contains status codes, headers, and a body.
• Status Codes: Indicate the result of the request (e.g., 200 OK, 404 Not Found, 500 Internal Server Error).
• Response body typically contains the HTML or content requested.

URL Structure

• Protocol: HTTP or HTTPS indicates the request type.
• Host: Domain name converted to an IP address.
• Path: Directs to the specific resource on the host server.
• Other optional parts: Authentication, Port, Query (parameters), and Fragment (page sections).

Cookies

• Small text files stored on the client-side, used to maintain state between sessions.
• Set by server responses and sent back by clients in subsequent requests.
• Can be manipulated or deleted by the client, impacting security.

Conclusion

• HTTP is essential for web operations, allowing resource requests and state management via cookies.
• Next lecture will focus on HTML, the structure of web content.
• Recommended tools: VS Code, Firefox, Chrome, and Postman for practicing HTTP requests.