The Redaction tool let's you completely eradicate the underlying content. It's not just a black rectangle, but a truly cut-out area, filled with black (or any other color you prefer). So it leaves no traces, there's nothing underneath something – the information is totally gone.

Simply using a black background color to cloak a black text (e.g. in Word or any other word processor) doesn't cut it, literally. The black background is just a shape, which can be deleted separately, revealing the text again...

Oorspronkelijk geplaatst op Quora: What is the redaction tool in Adobe Acrobat Reader?"