Lesson 47: Key Application Protocols: HTTP/HTTPS

HTTP and HTTPS are the backbone protocols of the World Wide Web, allowing clients and servers to exchange web documents and data.

HTTP (Hypertext Transfer Protocol)

• Layer: Application Layer (L7).
• Port: TCP Port 80.
• Function: HTTP is the protocol clients (browsers) use to send requests (GET, POST) to web servers and receive responses (HTML pages, images, status codes).
• Nature: HTTP is stateless, meaning the server does not retain any information about the client between requests (though cookies are used to overcome this limitation).

HTTPS (Hypertext Transfer Protocol Secure)

HTTPS is simply HTTP combined with a security layer, typically SSL/TLS (Secure Sockets Layer/Transport Layer Security).

• Port: TCP Port 443.
• Function: TLS operates below HTTP, encrypting all data exchanged between the browser and the server. This prevents eavesdropping and ensures data integrity.
• Requirement: To use HTTPS, the web server must possess an SSL/TLS digital certificate, which verifies the server's identity.

Security Note: You can recognize HTTPS by the padlock icon in your browser and the URL starting with https://. All sensitive web traffic (banking, login screens) must use HTTPS.