Does redacting a PDF actually remove the hidden text, or just cover it?

It actually removes it — marked areas are rebuilt as images first, so the underlying text genuinely can't be copied or recovered afterward.

Can I redact multiple areas across multiple pages?

Yes, drag over as many areas as needed across as many pages as the document has, then redact them all in one pass.

No — once redacted and downloaded, the covered content is permanently gone from that file, which is the point of true redaction.

永久塗黑敏感內容 —— 底層資料會被真正移除，而不只是被遮蓋而已。

將檔案拖放到這裡，或點擊瀏覽選擇

請選擇一個檔案

是真的移除——框選的區域會先重建成圖片，所以被遮蓋的文字之後真的沒辦法被複製或還原。

可以，不論文件有幾頁，都能框選需要的區域，然後一次全部塗黑。

不行——一旦塗黑並下載後，被遮蓋的內容就會從那份檔案中永久消失，這正是真正塗黑該有的效果。