Watermark

A watermark is text or an image laid over a PDF's pages to mark status or ownership, a faint "DRAFT" or "CONFIDENTIAL" diagonally across the page, a company logo, or a copyright line. It signals intent without obscuring the underlying content, usually by being semi-transparent or sitting behind the main text.

Technically a watermark is just more content drawn onto each page, with its own opacity, rotation and blend settings. There is an important distinction between an overlaid watermark, which is added as a separate layer and can in principle be removed, and a flattened one, which is merged permanently into the page so it cannot be peeled back off. For deterrence and traceability, flattening is the stronger option.

Watermarks are used for branding, for tracing leaks by stamping each recipient's copy differently, and for marking work as not-final. Applying them across a whole document is a per-page edit that runs comfortably in the browser, so you can stamp a sensitive draft without sending it through an external tool first.