Sensitive information is data whose unauthorized access, disclosure, alteration, or loss could harm people, organizations, or public interests. It can include personal identifiers, authentication secrets, financial and health records, proprietary business data, and information protected by law or contractual duty. Sensitivity depends on context: a data set may be restricted because of privacy obligations, competitive value, safety concerns, or national-security classification.
For security practitioners, the key issue is controlling the data throughout its lifecycle—from collection and use to storage, sharing, archiving, and deletion. Excessive privileges, exposed databases, insecure transfers, application logs, backups, and compromised accounts can all reveal sensitive data. Useful controls include data classification, least-privilege access, strong authentication, encryption in transit and at rest, retention limits, and monitoring for inappropriate access or transfer. A suspected exposure requires identifying what data was affected, preserving relevant evidence, containing access, and assessing privacy or regulatory notification duties.