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What is redaction?

Redaction is permanently removing sensitive information, such as names, account numbers or privileged passages, from a document before it is shared. In a PDF, true redaction deletes the text and images under each marked area from the file itself, rather than just covering them, and usually leaves a black box to show where content was removed.

Also called: Redact, PDF redaction

Updated October 14, 2026 · By the PDFZyro team

Why a black box isn't redaction

A PDF stores its text separately from what you see on the page. Drawing a black rectangle, highlighting in black or changing the text colour only adds something on top: the words underneath are still in the file. Anyone can select them, copy them out, find them with search or reveal them by converting the PDF to Word. Many redaction failures reported in the news happened exactly this way.

A proper redaction tool removes the content under each mark, the characters and the parts of pictures in the area. The black box that's left is only a marker.

What else to check

Sensitive information can also hide outside the page. The document's metadata may hold an author's name or an old title, bookmarks and comments may repeat a redacted name, and earlier saves can remain inside the file. Good practice is to redact the visible content, remove hidden data, and then check the result by searching for the words you redacted.

Redaction can't be undone in the redacted copy, so keep the original somewhere safe and share only the redacted version. In legal work, a redaction or privilege log may be needed to record what was removed and why.

When redaction is used

Lawyers redact privileged or confidential details before producing documents, public bodies redact personal data before releasing records, and businesses redact account numbers, addresses and Social Security numbers before sharing files with clients or suppliers. Privacy rules such as HIPAA for US health information and the GDPR in Europe are common reasons to redact personal data before a document leaves an organization.

Before you start, agree what must be removed. When the stakes are high, have a second person check the redacted copy before it's sent.

How to redact a PDF in PDFZyro

  1. Open the PDF with Redact.
  2. Select text, draw boxes over areas, or search for words and patterns such as emails, phone numbers or Social Security numbers to mark every match at once.
  3. Review the marks and apply them. The content underneath is removed and the redacted copy is saved as a new document; the original isn't changed.
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