====== Reserved Instances (RI) ======

**What it is:** A commitment-based discount model for EC2 (and some other services) for 1 or 3 years.

**What it’s for:**
  * Save money for steady-state, predictable workloads.

**Key ideas (exam-friendly):**
  * You commit to a term (1 or 3 years).
  * Lower cost than On-Demand.
  * Best when capacity needs are stable.

**Exam cues:**
  * “steady usage for 1 year, want lower cost” → RI.

**Hard words:**
  * *term* /tɝːrm/: kỳ hạn
  * *steady-state* /ˈstedi steɪt/: ổn định
  * *capacity* /kəˈpæsəti/: năng lực tài nguyên