Two Flavors: FaaS and BaaS

• FaaS (Functions as a Service): you upload functions (handlers) that the platform runs on demand (e.g., HTTP request, queue message, file upload). Examples: AWS Lambda, Google Cloud Functions, Azure Functions, Cloudflare Workers, Vercel Functions.
• BaaS (Backend as a Service): you consume managed backends (auth, storage, databases, messaging) via APIs without running them yourself.

Serverless architectures often mix FaaS glue code with BaaS building blocks.