What type of data does TLS primarily protect?

TLS (Transport Layer Security) primarily protects data in transit. This security protocol is designed to ensure privacy and data integrity when transmitting data over a network. It encrypts the data being sent between the sender and receiver, making it challenging for unauthorized parties to intercept and understand the information during transmission. This encryption safeguards against eavesdropping and tampering, which are significant threats in the context of data moving across potentially insecure networks such as the internet.

The other choices refer to different states of data. Data at rest pertains to inactive data stored physically in any digital form (like databases or files on a disk). Data in storage is somewhat synonymous with data at rest. Meanwhile, data left on devices refers to information that may be temporarily cached or saved on devices but is not actively being transmitted over a network. These states do not align with the specific function of TLS, which focuses solely on protecting data while it is being transmitted.