Use a text watermark for labels such as Confidential, Draft, Sample, or Approved. Image mode works well for a company logo, photographer mark, or department stamp. You can apply the mark to every page, odd or even pages, or a precise list such as 1, 3-5, 8.
The tool places a visual image layer over each selected PDF page without rasterizing the original page. Existing text and vector artwork keep their original representation. Because the PDF bytes change, keep the source file if it has a digital signature or must remain an exact archival record.