As I explore Art Nouveau style, I look for images that could be incorporated into my art. Wikimedia Commons is an excellent resource for public domain images. Public domain means that the image is no longer subject to copyright and anyone can use it. Rules for public domain can vary by country, but Wikimedia Commons does a good job of helping identify the status of an image. If you are a mixed media artist or a collage artist (paper or digital), these types of images can expand your artistic toolbox.