What it is: A managed service to create, publish, and secure APIs.

What it’s for:

• Build REST/HTTP APIs in front of Lambda, services, or other backends.
• Add authentication/authorization, throttling, and monitoring.

Key ideas:

• Common integrations:
  • Lambda (serverless APIs)
  • HTTP backends (ALB, EC2, on-prem)
• Supports features like caching, request validation, and usage plans (high-level).

Exam cues:

• “create an API for Lambda without servers” → API Gateway + Lambda.
• “rate limit API clients” → API Gateway throttling/usage plans.

Hard words:

• *publish* /ˈpʌblɪʃ/: công bố
• *backend* /ˈbækend/: hệ phía sau
• *throttling* /ˈθrɑːtlɪŋ/: giới hạn lưu lượng
• *validation* /ˌvælɪˈdeɪʃn/: kiểm tra hợp lệ