A watermark protects digital intellectual property, such as photos and artwork, from unauthorized use. It identifies the rightful owner of the work, which discourages other people from using it as their own.
A watermark is a visible overlay of copyright information (usually in the form of text or an image logo) added to photos or other digital documents. Image processing software programs, such as Photoshop, Paint.Net and Paint Shop Pro make it easy to design and add custom watermarks to photos. Watermarks are, however, not a foolproof method of protecting photos or artwork from unauthorized use; some people still publish watermarked photos on their websites. While it’s hard to prevent people from doing so, having a well-placed watermark containing a copyright symbol, name and URL of the owner can go a long way to discourage this.