Refers to data that is currently being processed or manipulated by a computer application or user. Unlike data at rest or data in transit, it’s in an active state, making it potentially more vulnerable to unauthorized access or attacks, like memory scraping. Security measures for data in use include encryption and access controls. Encrypting data in active use, also known as runtime encryption, involves protecting data being processed in a computer’s memory. Techniques include Trusted Execution Environments (TEEs) that create secure areas in a processor, Homomorphic Encryption that allows computations on encrypted data, and Secure Enclaves like Intel SGX, which safeguard data even if the system is compromised.