First, we'll talk about visible watermarks. You can make these easily in Adobe Photoshop or any image editor. Open up the image you want to watermark in Adobe Photoshop.



Select the "Horizontal Type Tool" on the toolbar on the left. The icon looks like the letter "T." Choose a font you like in the info bar at the top, any will do. Type out a text watermark like your name, you business name, or maybe your web site address. If the font size is too small, drag and highlight the text and change the font size at the top. The goal is to make it fairly big, but not too big, to deter image theft, but not obstruct viewing of the picture. Optionally, you may put your logo on a layer, instead of using text.



Now we want to rotate our watermark to maximize its coverage of the image, both horizontally and vertically. Press CTRL-T and left-click and drag right outside the watermark area. You will see two arrows in sort of a T formation and that lets you know you can rotate the watermark. Drag until the watermark is diagonally positioned.



Make sure the "Layers" palette is open. If it isn't, go to the "Window" menu and scroll down and left-click on "Layers."



Now we want to lower the opacity of the watermark, so it doesn't obstruct the picture as much. With the "Layers" palette open, select the watermark layer by left clicking on it. It is probably named whatever you typed in for the text of your watermark. You will know it is selected when it is highlighted. Go up to the "Opacity" field and click on the arrow and click and drag the slider down while looking at your watermark. Stop when you get an opacity you like. 35% Opacity is about right for me. Now you are finished with making your watermark! You make wish to duplicate the watermark layers and place them in other places on the image for added protection.



You may want to check out this article that shows you how to make a Photoshop action so you can easily watermark your images with the click of a button over and over again like a macro.

In addition to visible watermarks, there are various products out there, like Digimarc, that will embed your images with invisible watermarks. Some image editors, like Adobe Photoshop, will recognize these watermarks and notify the viewer that the image is copyrighted. Digimarc offers several versions of their watermarks at various prices. Some will allow you to track stolen images on the Internet.