Amazon Web Services
Serverless — AWS Lambda
Run code in response to events without provisioning or managing any servers.
AWS Lambda runs your function code on demand: you upload a handler, choose memory (CPU scales with it), and Lambda executes it when triggered, scaling from zero to thousands of concurrent executions automatically. You pay only for invocations and the compute milliseconds used, never for idle capacity. Lambda is the heart of event-driven, serverless architectures on AWS.
A motion-sensor light. It draws zero power in the dark and switches on instantly the moment someone walks by, for exactly as long as needed — you never pay to leave it burning all night.
Key Concepts
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Functions are invoked by a huge range of event sources: API Gateway (HTTP APIs), S3 (object created), DynamoDB/Kinesis Streams, EventBridge (scheduled or event-bus), SQS/SNS, and more. Key operational concepts are the cold start (first invocation initialises the runtime, adding latency), concurrency limits (and reserved/provisioned concurrency to control them), the 15-minute max execution time, and statelessness — persistent state lives in S3, DynamoDB, or other services.