Data protection is probably the central area of concern regarding system security. The proliferation of online systems means tension between data privacy and usability. The key to a usable but safe data environment is knowing what level of protection needs to be applied to different data, that is, how to classify data. In the past, this has been a predominantly manual and subjective exercise. As data volumes have expanded exponentially, there is a need for automated data classification systems. This lesson looks at the data classification technologies available through the Microsoft 365 compliance portal.