Creative Commons is a non-profit organization that has designed an easy way for you to share your creative work. Without relinquishing any of your copyrights, use a Creative Commons license to allow others to reproduce your copyrighted work and stipulate conditions that must be met. For example, you may require attribution and no commercial use. These and other conditions have been pre-bundled in various combinations; you pick one of these license bundles from the Creative Commons menu. A plug-in is available for Microsoft Office that simplifies this task.
2500 Creative Commons Licenses. Source, flickr: qthomasbower.
For an explanation of creative commons, watch this YouTube video by Justin Giugno