Article 9 of the EU General Data Protection Regulation defines “special categories” of personal data, such as health data, biometric data, political opinions, religion, trade-union membership, and sexual orientation. This data is treated as especially sensitive because misuse can create serious privacy, safety, or discrimination risks. In most cases, processing it is restricted unless a specific legal exception applies.
For cybersecurity teams, Article 9 matters because a breach involving special-category data usually has higher impact than an ordinary data leak. Attackers may seek it for extortion, identity profiling, or targeted social engineering, while defenders must reduce exposure through data minimization, strict access controls, encryption, retention limits, and careful logging. Security reviews and incident response should identify whether affected data falls under Article 9, since that changes the legal and technical handling requirements.