This document discusses functions-as-a-service (FaaS) and provides an introduction to using AWS Lambda. It outlines the advantages of FaaS such as infinitely scalable devops without server management. It demonstrates a basic "Hello World" Lambda function and connecting Lambda functions to MongoDB. It notes limitations such as cold start times and that database performance is more important than app servers for most use cases. It recommends FaaS for non performance-sensitive backends and provides further reading on serverless platforms and async/await.