AWS Lambda is an event-driven, serverless computing platform provided by Amazon as a part of Amazon Web Services. Therefore you don’t need to worry about which AWS resources to launch, or how will you manage them. Instead, you need to put the code on Lambda, and it runs.
In AWS Lambda the code is executed based on the response of events in AWS services such as add/delete files in S3 bucket, HTTP request from Amazon API gateway, etc. However, Amazon Lambda can only be used to execute background tasks.
AWS Lambda function helps you to focus on your core product and business logic instead of managing operating system (OS) access control, OS patching, right-sizing, provisioning, scaling, etc.