What is Microsoft Purview Information Protection?

Previously Azure Information Protection; applies sensitivity labels and encryption to email and documents.

Also called Azure Information Protection (AIP), Microsoft Information Protection.

In the Ultra Transcenders books

Each book explains Microsoft Purview Information Protection in context, with comparison tables and the common traps.

Azure Information Protection
Service that classifies and protects documents in Office apps, applying a single label to each (if several match, the last one in the policy wins). Its classic client has been retired, with Microsoft Purview sensitivity labels taking over.
Sensitivity labels
Purview's way of classifying, and if needed encrypting, content in Office apps and services. They take over from the classic labels of AIP.
Encryption
Scrambling data so it cannot be read without the correct secret key, which is then used to turn it back again. Hashing, by contrast, cannot be reversed.