A watermark is a small mark regularly containing a Scratcher's username or icon that is usually placed either in one of the four corners of the screen or on the art. The point of a watermark is supposed to help abolish art theft by the image and the mark being grouped together making it unable to remove. The usage of a watermark is also a good idea if participating in a MAP or a project similiar.
Types of Watermark
The username watermark is the best choice for a quick and easy mark as it is simply your username. Username watermarks are mainly used by newer Scratchers or Scratchers who don't feel as confident in their drawing abilities. If your username was 'Example' then you could type up 'Example' and place it above your art or where ever you feel your mark would be needed.