This document summarizes AWS Lambda and API Gateway. It discusses that Lambda allows developing microservice functions in a serverless environment with no server management needed and very low costs. API Gateway provides an interface for HTTP APIs and integrates with Lambda. While Lambda and API Gateway are easy to use and scale automatically with no servers to manage, there are some limitations and restrictions to consider like package size limits, processing time restrictions, and limited Node.js version support in Lambda. Testing APIs locally can also be challenging when using AWS services.