An HTTP client is code that sends HTTP requests to a server and reads HTTP responses back.

In Go, the standard library package `net/http` provides:

• helper functions like `http.Get`, `http.Post`, and
• the configurable client type `http.Client`.

• Call external REST APIs.
• Send webhooks.
• Download/upload data over HTTP/HTTPS.
• Communicate between microservices.

• Client: performs requests (`Do`, `Get`, `Post`).
• Request: method, URL, headers, body, context.
• Response: status, headers, body.
• Transport: controls connection pooling, proxies, TLS, timeouts (advanced).

package main
 
import (
    "io"
    "log"
    "net/http"
)
 
func main() {
    resp, err := http.Get("https://example.com")
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()
 
    b, _ := io.ReadAll(resp.Body)
    log.Println("status:", resp.Status)
    log.Println("bytes:", len(b))
}

• Always `defer resp.Body.Close()` to avoid leaking connections.
• Reuse an `http.Client` for many requests (do not create a new one every time).
• Use timeouts (client timeout or request context) to avoid hanging forever.
• Validate status codes before trusting the response body.

• HTTP server overview
• http.Client
• http.Server
• context.Context

• client /ˈklaɪənt/: phía gọi (bên gửi request)
• request /rɪˈkwest/: yêu cầu
• response /rɪˈspɑːns/: phản hồi
• leak /liːk/: rò rỉ (tài nguyên/kết nối)
• reuse /ˌriːˈjuːz/: tái sử dụng
• timeout /ˈtaɪmaʊt/: hết thời gian chờ
• hanging /ˈhæŋɪŋ/: treo/chờ mãi
• transport /ˈtrænspɔːrt/: tầng vận chuyển (cách kết nối HTTP)
• pooling /ˈpuːlɪŋ/: gom/tái sử dụng (kết nối)