What is AWS Lambda and when to use it

Short answer

AWS Lambda runs code in response to events without managing servers. You pay per request and compute time. It excels at event-driven, intermittent workloads but is less suitable for long-running or consistently high-throughput applications.

Details

Lambda integrates with over 200 AWS services. Common triggers include API Gateway (HTTP), S3 (file uploads), SNS/SQS (messages), and EventBridge (scheduled tasks). Functions have a 15-minute execution limit and configurable memory up to 10 GB. Cold starts occur when a new execution environment is provisioned; provisioned concurrency mitigates this for critical paths.

Serverless architectures pair well with event-driven design. To explore this pattern further, see How to build event-driven architecture in the cloud. If you are comparing cloud providers, read What is Azure Functions and how does it compare to AWS Lambda.

Tips

• Keep deployment packages small to reduce cold start latency.
• Use Lambda Power Tuning to find the optimal memory/CPU balance for your function.
• For local testing, how to build a Docker image can containerize Lambda runtime environments for consistent development.