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HTTP (Hypertext Transfer Protocol) is the main protocol for web exchange. The client sends a request to the server (e.g., GET to retrieve a page), the server processes the request and sends a response (page, data, status). The state is not maintained between requests (stateless).

HTTPS is the secure version of HTTP. It uses TLS/SSL to encrypt data between the client and the server, ensuring confidentiality and integrity of the transmitted information.

TCP (Transmission Control Protocol) is a transport layer protocol. It establishes a reliable connection between sender and receiver. It guarantees the delivery of packets in the correct order, performs retransmissions in case of loss. Used for HTTP, HTTPS, FTP.

UDP (User Datagram Protocol) is a connectionless transport layer protocol. It sends data packets without guarantee of delivery, order, or retransmission. It is faster than TCP, used for streaming video, online games, DNS.

DNS (Domain Name System) converts domain names (e.g., example.com) into IP addresses. It works as a distributed database. When a user enters a domain name in the browser, the browser sends a DNS request to obtain the corresponding IP address, which is then used to connect to the web server.

Example of an HTTP request and response:

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

// Server response
HTTP/1.1 200 OK
Content-Type: text/html
Content-Length: 1234

<!-- HTML code of the page -->

Comparison of TCP and UDP:

Feature	TCP	UDP
Delivery reliability	Guaranteed	Not guaranteed
Ordered delivery	Yes	No
Connection setup	Required (three-way handshake)	Not required
Speed	Lower	Higher
Usage examples	HTTP, HTTPS, FTP	DNS, streaming video, games