Data security is the practice of protecting sensitive information from unauthorized access, loss, corruption, or misuse. It combines controls such as access management, encryption, backup, logging, and data classification so organizations know what data they have, where it is stored, and who can use it. Strong data security is not only about keeping attackers out; it also limits harm when systems are misconfigured or when insiders overreach their permissions.
In cyber security, data security matters because many attacks ultimately aim at information: customer records, credentials, intellectual property, or operational data. Defenders use it to reduce exposure, detect abnormal access, and recover after incidents. Common defenses include least-privilege access, multi-factor authentication, encryption at rest and in transit, and data loss prevention tools. In real attacks, stolen data is often copied, exfiltrated, or encrypted for extortion, which makes good data security a core control against both theft and ransomware.