A data breach is the unauthorized access, disclosure, or exposure of protected information. The data may be personal records, credentials, logs, or internal service data, and the breach can happen through hacking, misconfiguration, stolen accounts, or a compromised partner system.
In cyber security, breaches matter because exposed data can be used for phishing, account takeover, identity abuse, or further intrusion. Cloud and partner-run services are common examples: if a regional operator stores user records, attackers may target that database even when the main application remains online. Defenses include limiting access, encrypting sensitive records, monitoring for unusual queries or logins, securing backups, and rotating credentials after suspicious activity. A breach is not just data loss; it is a failure of trust boundaries and access control.