====== ElastiCache ======

**What it is:** A managed in-memory caching service (Redis or Memcached).

**What it’s for:**
  * Reduce database load and speed up responses.
  * Store session data, frequently accessed data, leaderboards.

**Key ideas:**
  * Two engines:
    * [[aws:database:elasticache:redis|Redis]]
    * [[aws:database:elasticache:memcached|Memcached]]
  * Cache is typically used in front of RDS/DynamoDB.

**Exam cues:**
  * “reduce read load on DB” → ElastiCache.
  * “millisecond response for repeated reads” → caching.

**Hard words:**
  * *in-memory* /ɪn ˈmeməri/: trong RAM
  * *caching* /ˈkæʃɪŋ/: lưu đệm