A watermark is a recognizable image or pattern embedded into paper or digital content, often used to indicate authenticity or ownership. In physical documents, watermarks are created during the paper-making process, making them difficult to replicate. They can be seen when the paper is held up to the light and are commonly used in currency, legal documents, and stationery. In digital media, watermarks are often used to protect images, videos, or documents from unauthorized use. These digital watermarks can be visible, like a logo or text overlay, or invisible, embedded within the file's data. They help creators maintain control over their work and deter copyright infringement.