DevOps Dictionary

AWS Lambda is a serverless compute service that runs your code in response to events, such as an API request, a file upload to Amazon S3, a message arriving on a queue, or a scheduled timer, without you provisioning or managing servers. You package a function (a small unit of code) and configure an event source; Lambda then automatically starts the function when the event occurs, scales the number of concurrent executions up or down based on demand, and charges only for the time your code runs.

With AWS Lambda, teams can build event-driven systems quickly and reduce operational overhead; without it, you typically run always-on services or batch workers that require capacity planning, patching, and ongoing monitoring even when idle. This gap exists because Lambda abstracts the underlying fleet management and scaling logic, so you focus on application logic while AWS handles execution environments and elasticity.