Draw black boxes over sensitive text or images before sharing a document. The tool permanently flattens those redactions into the page so the hidden content can't be recovered by selecting text underneath.
A common mistake is covering sensitive text with a shape in a regular PDF viewer. The box sits visually on top, but the text is still there underneath, recoverable by anyone who selects it or deletes the shape. Real redaction has to remove the underlying content, not just hide it.
After you draw your redaction boxes, the affected page gets rebuilt as a flattened image with the black boxes baked into the pixels. There's no separate text layer or shape to peel back afterward.
Yes, the page is rebuilt as a flattened image with the box baked in, unlike simply drawing a shape on top which someone could move or delete.
Redactions are drawn and saved per page. For a mark repeated on every page, Watermark PDF is a better fit.
That page becomes an image, so its text is no longer selectable. That's intentional, since it's what makes the redaction permanent.
Use Clear Boxes on This Page before saving to remove marks and redraw them. Nothing is finalized until you save.