PII, or Personally Identifiable Information, refers to any data that can be used to identify a specific individual. This includes obvious details like names, addresses, and social security numbers, but can also encompass less direct identifiers such as email addresses, phone numbers, or biometric data. Protecting PII is crucial because its exposure can lead to identity theft, financial fraud, or privacy violations. Organizations are often legally required to safeguard PII and handle it responsibly to prevent unauthorized access or misuse.