TCP (Transmission Control Protocol) is a transport-layer protocol. It provides a reliable, ordered byte-stream connection between two endpoints (client and server).

TCP is like a pipe that carries bytes.

HTTP (Hypertext Transfer Protocol) is an application-layer protocol. It defines how to format requests and responses (methods like GET/POST, headers, body, status code).

HTTP runs on top of TCP (most commonly).

• TCP does NOT have “methods”.
• HTTP has methods (GET/POST/PUT/DELETE), and those methods are just text/bytes sent through TCP.

So the correct mental model is:

• TCP = connection + byte stream
• HTTP = rules for what bytes mean

• Application layer: HTTP (request/response format)
• Transport layer: TCP (reliable connection)
• Network layer: IP (routing packets)

You can open a TCP connection and send an HTTP request manually:

conn, _ := net.Dial("tcp", "example.com:80")
defer conn.Close()
 
fmt.Fprint(conn, "GET / HTTP/1.1\r\nHost: example.com\r\nConnection: close\r\n\r\n")
io.Copy(os.Stdout, conn)

Instead of crafting bytes yourself, use `http.Client`:

resp, err := http.Get("http://example.com/")
if err != nil { return }
defer resp.Body.Close()

• Use http.Client when the server speaks HTTP/HTTPS (REST APIs, web, webhooks).
• Use net.Dial when you need raw TCP for a non-HTTP protocol (Redis/MySQL/custom protocols).

• transport layer /ˈtrænspɔːrt ˈleɪər/: tầng vận chuyển
• application layer /ˌæplɪˈkeɪʃən ˈleɪər/: tầng ứng dụng
• protocol /ˈproʊtəkɔːl/: giao thức
• byte stream /baɪt striːm/: luồng byte
• reliable /rɪˈlaɪəbəl/: đáng tin cậy
• ordered /ˈɔːrdərd/: đúng thứ tự
• endpoint /ˈendpɔɪnt/: điểm kết nối (client/server)
• craft /kræft/: tự “chế”/tự tạo