What it is: A script/commands you provide at launch that run automatically on first boot.

What it’s for:

• Install packages, pull code, configure services at startup.
• Bootstrap instances in an automated way.

Key ideas:

• Runs once at instance initialization (by default).
• Common for installing web servers, setting environment configs.

Exam cues:

• “install software automatically when instance launches” → user data.

Hard words:

• *bootstrap* /ˈbuːtstræp/: khởi tạo tự động ban đầu
• *initialization* /ɪˌnɪʃələˈzeɪʃn/: quá trình khởi tạo