====== Lifecycle Rules ======

**What it is:** Rules that automatically transition objects between storage classes or expire/delete them.

**What it’s for:**
  * Reduce cost (move old data to cheaper storage).
  * Automatically delete data after a retention period.

**Key ideas:**
  * Can transition: Standard → IA → Glacier, etc.
  * Can expire current versions and noncurrent versions (when versioning is on).

**Exam cues:**
  * “move logs to Glacier after 90 days” → lifecycle transition.
  * “delete files after 1 year” → lifecycle expiration.

**Hard words:**
  * *transition* /trænˈzɪʃn/: chuyển đổi
  * *expire* /ɪkˈspaɪər/: hết hạn
  * *retention* /rɪˈtenʃn/: thời gian lưu giữ