Event-driven architecture provides developers with increased availability, elasticity, scalability, and cost optimization. With the rise of microservices and the cloud, event-driven architecture is becoming increasingly important for developers to understand.

AWS Lambda is very good fit with event-driven architectures, because the nature of lambda executions trigger from events. Events can come lots of resources and able to trigger lambda functions.

The main purpose of AWS Lambda functions is to handle events.

An event triggering a Lambda function could be almost anything, you can see in the image, from REST API HTTP request with Amazon API Gateway, a schedule task managed by an Amazon EventBridge rule, or an Amazon S3 notification like object uploaded into bucket.

Even the simplest Lambda-based application uses at least one event. So that's why we said, AWS Lambda is very good fit for the Event-Driven Architectures. Because the fuel of AWS Lambda is events.

https://medium.com/aws-serverless-microservices-with-patterns-best/event-driven-serverless-microservices-design-with-aws-lambda-bfc6ab2881eb