A watermark is a faint image or text that is permanently included in the image file, marking it as your work. It is a good way to deter copying of your images as anyone seeing the image can immediately see that it is your work.
Copyright registration of photographic work is simple and cost effective; photographers can submit a collection of tens, hundreds or even thousands of images for a single registration fee.
Exploring copyright in photography, the rights of photographers, registration advice and specific considerations that apply to photographs.