====== Object ======

**What it is:** A file stored in S3, plus metadata, stored under a key (path-like name).

**What it’s for:**
  * Store and retrieve files using the object key.
  * Attach metadata (content-type, tags, custom metadata).

**Key ideas:**
  * Object identity = bucket + key.
  * S3 is not a real “folder” system—folders are part of the key naming.
  * You can set permissions via ACLs (less preferred) or policies.

**Exam cues:**
  * “S3 folder isn’t real” → it’s a prefix in object keys.

**Hard words:**
  * *metadata* /ˈmetəˌdeɪtə/: siêu dữ liệu
  * *prefix* /ˈpriːfɪks/: tiền tố
  * *content-type* /ˈkɑːntent taɪp/: loại nội dung (MIME type)