I thought this info was worth sharing. I have been using public domain art for years, however the world of information sharing has grown beyond belief. It is pretty easy to see a Matisse as public domain, not so easy with the billions of images floating around on Google, Bing and Pintrest! If you are putting your original artwork anywhere on the internet I advise you to watermark it. If you don't there are a lot of business and people out there trolling for images and they will use and may even take credit and earn from your work!
Please note the credits and my thanks to The Blue Bottle Tree for sharing!