What does 'serverless computing' mean in cloud architecture?

In serverless (FaaS — Function as a Service), developers write stateless functions triggered by events (HTTP requests, database changes, file uploads). The cloud provider (AWS Lambda, Azure Functions, Google Cloud Functions) handles all infrastructure — provisioning, scaling, patching. Billing is per invocation and execution duration (millisecond precision). Use cases in banking: fraud detection triggers, transaction notification functions, scheduled report generation, API backend processing. No idle costs are incurred.