You can watermark your PDF with text, logo, or image to let people know that the PDF is private, confidential, or created by you or your organization. Though a watermark can’t prevent content theft, it certainly can prevent misuse and help convey that you’re the creator or owner of that PDF.
So, whether it is for school, work, or personal use, this tutorial will show you how to watermark PDFs for free on your iPhone, iPad, and Mac.