> For the complete documentation index, see [llms.txt](https://help.nightfall.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.nightfall.ai/faqs/data_tagging.md).

# Does Nightfall require data to be already tagged?

No, Nightfall doesn’t require data to be pre-tagged. Nightfall uses machine learning to detect 100+ types of sensitive data out of the box, without prior tuning or tagging required. This includes forms of PII, PHI, PCI, and other sensitive content – for example, emails, social security numbers, etc. Our detectors leverage context surrounding a specific token to properly identify and classify it, which dramatically improves accuracy over traditional rules-based approaches to DLP.


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