While performing ETL operations and transformations, how will you handle PII data?

First, I identify PII fields during the extraction phase using a data catalog or schema registry. Next, I classify the sensitivity level (e.g., personal identifiers, financial data). For transformation, I apply one of the following techniques:

1. Masking: replace characters with asterisks or hash patterns for display purposes.
2. Tokenization: substitute PII with a non‑reversible token stored in a secure token vault.
3. Encryption: use AES‑256 or AWS KMS to encrypt PII before loading into the target.

I also enforce strict access controls: only authorized services and users can decrypt or view the data. Auditing is enabled via logs and data lineage tracking. Finally, I validate compliance with regulations (GDPR, CCPA) by generating reports that confirm PII handling steps were executed.