CloudTrail is an AWS service that records API calls made in an AWS account and delivers log files to enable security monitoring and compliance. It provides visibility into who accessed AWS resources, when they accessed them, and from where. Cloudlytics is a service that allows users to analyze CloudTrail logs to generate security and compliance reports. The document discusses enabling CloudTrail, configuring Cloudlytics to access CloudTrail logs, and using Cloudlytics to analyze the logs and generate various audit reports.