Serverless is a cloud model where you write functions or applications and the platform provisions, scales, and bills them per invocation — you never provision or maintain servers. AWS Lambda, Vercel Functions, Cloudflare Workers, Google Cloud Functions, and Azure Functions are the leading platforms.
Benefits: zero server management, automatic scaling to demand (including to zero when idle), pay-per-execution billing. Trade-offs: cold starts, execution time limits, vendor lock-in, and complex debugging.
Best fits: API endpoints, webhooks, event processing, scheduled jobs, image processing, CI/CD steps. Poor fits: sustained-load web servers, applications with strict latency SLAs on every request, workloads requiring persistent in-memory state.