FaaS

FaaS (Function as a Service) is the compute model at the heart of serverless: you deploy individual, stateless functions that the platform runs in response to events (an HTTP request, a file upload, a queue message), scaling each independently and billing per invocation. AWS Lambda, Google Cloud Functions, and Azure Functions are FaaS.

Worked example: instead of an always-on server, you deploy a single handleUpload() function; the platform spins it up per event, runs it, and tears it down — you write business logic, not server code. Gotcha: FaaS functions are stateless and short-lived, so state must live elsewhere (a database, cache), cold starts hit the first call, and chaining many functions creates distributed-systems complexity (tracing, error handling across functions) — FaaS is one piece of serverless, alongside serverless databases, queues, and storage.