AWS Lambda integrates with other AWS services

to invoke functions or take other actions.

▪ There is an event source or trigger, and actual

Function code and then there is the destination.

▪ Event source has a number of services; they can

be a http call, cron job, uploading an object into S3

bucket, third party call like payment done through

stripe

▪ Triggering event to lambda function, lambda launch

the execution environment with different language

and runtimes

▪ Lambda has destinations that can be interaction

with your function code 

https://medium.com/aws-serverless-microservices-with-patterns-best/aws-lambda-event-sources-and-destination-trigger-services-8e9f1f5625d8