You can use access and usage reports to gain visibility into the integrity and security of your organization's Azure Active Directory tenant. With this information, you can identify security risks and be able to adequately plan for mitigating those risks.
In the Azure Management Portal, reports are categorized in the following ways:
Anomaly Reports: Contains sign-in events that were found to be anomalous
Integrated Application Report: Provides insight into how cloud applications are being used in your organization
Error Reports: Indicates errors that may occur when provisioning accounts to external applications
User-specific Reports: Displays device/sign in activity data for a specific user