The term watermark comes from the way these designs are created, during the "wet paper" stage of making paper, and also from the fact that a watermark resembles a damp spot. Documents, stamps, and paper money all have watermarks that label them as genuine. Fancy writing paper often includes watermarks noting the brand.

Watermarking is the process of superimposing a logo or piece of text atop a document or image file, and it's an important process when it comes to both the copyright protection and marketing of digital works.

Obvious examples of watermarks include shaded text phrases like “Top Secret”, “Confidential”, and “Internal Use Only”. A watermark saying “Test” is one that is often overlooked. Yet it can be very useful in safeguarding information in perhaps a different way.

an image behind the main text of a computer document, for example, in official company documents or in documents used when giving a talk: A watermark is more transparent than a background and is often used as a way to display company logos during a presentation.

A Branding Watermark is a YouTube feature that allows creators to add a branded image (typically a logo) to all of the videos on that channel.

Insert a watermark On the Design tab, select Watermark. Choose a pre-configured watermark, like DRAFT, CONFIDENTIAL, or DO NOT COPY. For placing a logo or image, Select Watermark > Custom Watermark > Picture watermark > Select Picture. On the same menu you can create a custom text watermark.

Add or edit a text watermark On your computer, open a document in Google Docs. Go to Insert. Watermark. In the panel on the right, click Text. Type the text you want to appear as a watermark. Optional: In the panel on the right, you can format your watermark. Click Done.