Data states

Data states describe the three conditions information occupies: at rest, sitting in storage; in transit (also called in motion), moving across a network; and in use, held in memory while being processed. The model matters because no single control covers all three states, so every protection question starts by asking which state the data is actually in.

Each state maps to its own controls. At rest calls for encryption of disks, databases, and backups, typically with symmetric encryption for bulk data. In transit calls for encrypted channels: TLS for application traffic, IPsec for network-layer tunnels. In use is the hardest state, because data must generally be decrypted before it can be processed; protections here are memory management, process isolation, and increasingly hardware enclaves and homomorphic encryption. A control from the wrong state gives no protection at all: full-disk encryption is worthless once the file is travelling over an open network.

Exam relevance: if a scenario tells you where the data is, it is telling you which control family to pick: storage means encryption at rest, network means TLS or IPsec, processing means memory protections. The nearest confusable is treating encryption as one answer: encryption at rest and encryption in transit are separate controls solving separate exposures, and data remanence reminds you that at-rest protection must extend all the way to the media’s disposal.