Creative Commons is a nonprofit organization that offers customizable copyright licenses. They are adapted to fit nearly any purpose you have in protecting your work (audio, text, images, etc...).
For instance, work in this book is subject to their license, that you can find at the bottom of the page.
To use one of their license, go to their website and describe what and how you want to protect, they will output you the code that you have to integrate on your pages.
