`http.Client` is Go’s HTTP client used to send requests and receive responses. It supports connection pooling and keep-alive by default.

• Call external APIs (GET/POST/PUT/DELETE).
• Set timeouts and transport options.
• Reuse connections efficiently.

package main
 
import (
    "io"
    "log"
    "net/http"
    "time"
)
 
func main() {
    client := &http.Client{
        Timeout: 5 * time.Second,
    }
 
    resp, err := client.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("body bytes:", len(b))
}

package main
 
import (
    "bytes"
    "log"
    "net/http"
    "time"
)
 
func main() {
    client := &http.Client{Timeout: 5 * time.Second}
 
    req, _ := http.NewRequest("POST", "https://example.com/api", bytes.NewBufferString(`{"a":1}`))
    req.Header.Set("Content-Type", "application/json")
 
    resp, err := client.Do(req)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()
 
    log.Println("status:", resp.StatusCode)
}

• Always `defer resp.Body.Close()` to avoid leaking connections.
• Prefer a reusable `http.Client` (do not create a new client per request in hot code).
• Set `Timeout` (or use request context) to avoid hanging forever.
• For advanced control, customize `Transport` (proxy, TLS settings, connection limits).

• HTTP client
• net/http
• context.Context

• request /rɪˈkwest/: yêu cầu
• response /rɪˈspɑːns/: phản hồi
• connection pooling /kəˈnekʃən ˈpuːlɪŋ/: gom/tái sử dụng kết nối
• reuse /ˌriːˈjuːz/: tái sử dụng
• leak /liːk/: rò rỉ (tài nguyên)
• hang /hæŋ/: treo, chờ mãi
• transport /ˈtrænspɔːrt/: tầng vận chuyển (cấu hình cách client kết nối)