Papermaking techniques were brought to Europe in the 12th century, but the practice of placing a watermark in paper made of rags did not begin until the early 13th century. Under the assumption that watermarks were used as the paper maker's trademark, studies began in the 18th century to identify where and when the paper was produced. In the early 20th century, C. Briquet, a Swiss researcher, published a collection of watermarks entitled Les Filigranes. Today, a project to create a watermark database is under way.
For details, visit the World of Watermarks.