PHI, or Protected Health Information, refers to any personal health data that can identify an individual and is created, received, or maintained by healthcare providers, insurers, or related entities. This includes medical records, test results, billing information, and any other data linked to a person's health status or care. PHI is protected by laws such as HIPAA in the United States, which set strict rules for how this sensitive information must be handled, stored, and shared to ensure privacy and prevent unauthorized access. Cybercriminals often target PHI due to its high value on the black market.