How do data pass from the client to the server during an HTTP request? Describe all stages.

During an HTTP request, data passes through several key stages from the client to the server:

1. Forming the request on the client — the browser or another client application creates an HTTP request, including the method (GET, POST, etc.), URL, headers, and body (if any).

2. DNS resolution — the client converts the server's domain name into an IP address via a DNS query.

3. Establishing a TCP connection — the client establishes a TCP connection with the server using the obtained IP and port (usually 80 for HTTP or 443 for HTTPS).

4. TLS handshake (if HTTPS) — if HTTPS is used, a secure channel is established using TLS.

5. Sending the HTTP request — the formed HTTP request is sent over the established connection.

6. Server processes the request — the server receives the request, parses it, processes business logic, interacts with databases, and forms a response.

7. Sending the HTTP response — the server sends back an HTTP response with a status code, headers, and body.

8. Client receives and processes the response — the client receives the response, parses it, displays data to the user, or processes it further.

9. Closing or reusing the connection — the TCP connection may be closed or reused (keep-alive).

Each of these stages involves interaction at different levels of the network model — from the application layer (HTTP) to the transport layer (TCP) and network layer (IP).