===== time package =====

==== What is it? ====
`time` is Go’s standard library package for working with:
  * current time
  * durations
  * sleeping/timers
  * parsing and formatting dates/times
  * time zones and locations

==== What is it used for? ====
  * Create timestamps for logs/events.
  * Measure elapsed time and performance.
  * Set timeouts and deadlines (often with `context`).
  * Schedule work with timers/tickers.
  * Parse/format time strings (RFC3339, custom layouts).

==== Core types ====
  * `time.Time`: a point in time (date + time + location)
  * `time.Duration`: a length of time (e.g., 200ms, 5s)
  * `time.Location`: time zone info (e.g., UTC, Asia/Ho_Chi_Minh)

==== Core functions (most common) ====
  * `time.Now()`: current local time
  * `time.Since(t)`: elapsed duration since `t`
  * `time.Until(t)`: duration until `t`
  * `time.Sleep(d)`: sleep for duration `d`
  * `time.Parse(layout, value)`: parse string into `time.Time`
  * `t.Format(layout)`: format `time.Time` into string
  * `time.NewTimer(d)`: one-shot timer
  * `time.NewTicker(d)`: periodic ticker

==== Example: current time ====
<code go>
now := time.Now()
fmt.Println(now)
</code>

==== Example: measure elapsed time ====
<code go>
start := time.Now()
// do work...
elapsed := time.Since(start)
fmt.Println("elapsed:", elapsed)
</code>

==== Example: sleep ====
<code go>
time.Sleep(500 * time.Millisecond)
</code>

==== Example: parse + format (RFC3339) ====
<code go>
t, err := time.Parse(time.RFC3339, "2026-01-09T10:30:00+07:00")
if err != nil { return err }

s := t.Format(time.RFC3339)
fmt.Println(s)
</code>

==== Example: custom layout (Go layout rule) ====
Go uses a reference time to define layouts:

==== Child pages:==== 
* [[go:time:Go_time_layout_reference|Go time layout reference]]
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