PII Redaction

PII redaction identifies spans of text containing information that could identify a specific individual — names, addresses, phone numbers, email addresses, government ID numbers, and similar — and masks or removes them before data is used for training or shared with a broader team. It's a required step for any dataset sourced from real user interactions rather than synthetic or already-anonymized text.

This work is closely related to named entity recognition in technique (finding spans of a specific type) but differs in purpose: NER labels entities to preserve information, while PII redaction removes it. Getting the boundary right matters just as much — under-redaction leaves sensitive data exposed, while over-redaction can strip context a model actually needs.

PII redaction is one part of the broader practice of privacy-preserving annotation, which also covers access controls and minimizing what annotators see in the first place.