Creative Commons and Copyleft
Creative Commons allows for a creative person to apply varying degrees of copyright to their works. You can allow someone different privelages regarding your work, and you are also always protected under the usual copyright law. "Creative Commons licenses give you the ability to dictate how others may exercise your copyright rights—such as the right of others to copy your work, make derivative works or adaptations of your work, to distribute your work and/or make money from your work. They do not give you the ability to restrict anything that is otherwise permitted by exceptions or limitations to copyright—including, importantly, fair use or fair dealing—nor do they give you the ability to control anything is not protected by copyright law, such as facts and ideas."
Find out more about the Creative Commons here.
Copyleft is a way to make your creative work free to others, for them to modify and alter and change. "Copyleft says that anyone who redistributes the software, with or without changes, must pass along the freedom to further copy and change it. Copyleft guarantees that every user has freedom."
Find out more about Copyleft here.
I downloaded a photo from Flickr that was copyleft--altered it and now will collab with another artist with it. Thank you copyleft. I do these things sometimes anyhow, without the copyleft arrangment. But there is always this little nagging worry if you want to get technical about stuff. I have to support efforts to change a messed-up system. Even if the alternatives aren't always ideal.