In Adobe Bridge select all the photos you want to rename. If they’re all in one folder then choose Edit> Select All. (If you’re using Photoshop CS, Batch Rename is in the File Browser then choose Automate> Batch Rename). Then choose Tools>Batch Rename and follow the prototype of the setup in the image above. In this case, I want all my images to say the word "small" after their file name. A choice can also be made to have all the images have the same name but in a numerical sequence. Such as pelican 001_small.jpg, pelican 002_small.jpg, pelican 003_small.jpg and so forth...

I highly suggest you practice with a few images in a duplicate folder of images first until you are comfortable with the command. Nevertheless, you don’t have to use “Copy to Another Folder”. I just set it that way for security and not to lose images in case of error.