CloudWatch Events are a concept particular to AWS. You can see them as a hybrid of logs and metrics. Events have identifiers and context the same way metrics have a name and a resources ID, but they can also carry a payload with custom information. AWS uses it extensively in their infrastructure and services. Every time resources in your environment change, AWS creates an event that goes into a stream that the CloudWatch events service can subscribe to. You can create rules to match events of interest and either send the information to a service, such as SQS or SNS, or directly execute code using some pre-program functionalities or Lambda.