`bufio` implements buffered I/O by wrapping an `io.Reader` or `io.Writer` and using an in-memory buffer to make reading/writing more efficient.

• Faster reading/writing for files and network connections.
• Convenient scanning of lines/tokens (`bufio.Scanner`).
• Convenient line-based reads (`ReadString`, `ReadBytes`).

• `bufio.Reader`: buffered reader
• `bufio.Writer`: buffered writer
• `bufio.Scanner`: token/line scanner

r := bufio.NewReader(f)
line, err := r.ReadString('\n')
_ = line
_ = err

w := bufio.NewWriter(f)
_, _ = w.WriteString("hello\n")
_ = w.Flush()

• Always call `Flush()` on `bufio.Writer` to ensure data is written.
• `Scanner` has a token size limit by default; for big lines, configure buffer or use `Reader`.

• io package
• os.Open
• net.Dial

• buffer /ˈbʌfər/: bộ đệm
• wrap /ræp/: bọc
• efficient /ɪˈfɪʃənt/: hiệu quả
• flush /flʌʃ/: đẩy hết dữ liệu trong buffer ra nơi ghi
• token /ˈtoʊkən/: đơn vị tách (mảnh dữ liệu)