Copyright is a set of rights provided by the laws of the United States (Title 17, U.S Code). The U.S. Copyright Office defines copyright as "a form of protection grounded in the U.S. Constitution and granted by law for original works of authorship fixed in a tangible medium of expression." It is derived from the Copyright Clause of the Constitution, which empowers Congress "[t]o promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries."
As the author of a DNP project, you already own the copyright to your work. Under U.S. Copyright law, a creator of an "original work" created in a "fixed tangible medium" is immediately and automatically the copyright owner of the work.
For more information about copyright,
visit the copyright guide.
Registration with the U.S. Copyright Office is optional but recommended. The registration gives you the right to sue over copyright infringements and allows you to be awarded damages and attorney fees in an infringement action. It also provides some other benefits such as establishing a public record of your project and copyright. Registration is required before you can have these benefits.
Attribution (CC BY). Allows others to distribute, remix, tweak, and build upon your work, even commercially, as long as they credit you for the original creation.
Attribution-ShareAlike (CC BY-SA). Allows others to remix, tweak, and build upon your work even for commercial purposes, as long as they credit you and license their new creations under the identical terms.
Attribution-NoDerivs (CC BY-ND). Allows others to distribute your work, commercially or non-commercially, as long as it is passed along unchanged and in whole, with credit to you.
Attribution-NonCommercial (CC BY-NC). Allows others to remix, tweak, and build upon your work non-commercially. Although others must acknowledge you and use your work non-commercially, they don’t have to license their derivative works on the same terms.
Attribution-NonCommecial-ShareAlike (CC NC-SA). Allows others to remix, tweak, and build upon your work non-commercially, as long as they credit you and license their new creations under the identical terms.
Attribution-NonCommercial-NoDerivs (CC BY-NC-ND). Allows others to download your works and share them with others as long as they credit you, but they can’t change them in any way or use them commercially.
(Adapted from creativecommons.org)