AWS CloudTrail is a service provided by AWS, which records AWS API calls for your account and stores the log files in the S3 bucket. It will also give you the information related to the recent activity that took place in AWS account via the CloudTrail dashboard. This information includes the time of the API call, identity of the API caller, source IP address of API caller, the request parameters, and the response elements returned by the AWS service.
CloudTrail can give you a history of all the API calls for your account, whether the API calls have been made via Console, SDKs, CLI, or higher-level services such as CloudFormation. This record of history enables security analysis as well as compliance auditing and resource change tracking.
Understanding CloudTrail logs could become a bit challenging...