If you are tired of having your online photos / images copied by someone else, you need to watermark your images. There are very rare chances that people might copy the watermarked images too. In fact, by copying your watermarked image, they’ll be showing your name or URL in the watermark, hence publicizing you!
Of course, Photoshop users can Watermark their images easily (see how to watermark images in Photoshop), but those who don’t use Photoshop can use these cool Online Watermark Generator Tools to watermark photos and images online:
Also see Best tools to Optimize CSS Online.