Copyright. Copyright is designed to protect the creator from having their creation stolen or copied. Copyright protects music, poetry, art, photography, and many other mediums that are considered in a "fixed state." Copyright happens the moment the work is created. If you are an author, artist, or creator of some kind, be sure and apply for copyright and be careful about sharing to the whole world on the internet.
Fair Use. Students and teachers have some leeway in using copyrighted material as long as it is for educational purposes. This does not mean that you can simply ignore copyright. Be careful to always cite books, articles, music, art, photography and other copyright-protected media in every type of project or paper.
Public Domain. Works that are not covered by individual copyright are considered available for the public to use without permission. Works that have expired copyright can be used without permission. Works in the public domain include the Bible and some similar religious texts, fairy tales and folk tales, government publications and documents. Depending on the citation method you are using, you may need to cite these sources
The Random House dictionary defines plagiarism as "the unauthorized use or close imitation of the language and thoughts of another author and the representation of them as one's own original work."
There are two kinds of plagiarism; intentional and unintentional.
Intentional plagiarism means that you are doing it on purpose. You know that you are doing something wrong. There are three types of intentional plagiarism.
Unintentional plagiarism means that you have plagiarized, but not on purpose. Most unintentional plagiarism happens when you are rushing due to poor time management. Be sure you give yourself plenty of time. Learn how to do citations properly. Be careful as you write to incorporate information from sources as quotes or paraphrasing.
Paraphrasing means that you have put information from a source into your own words. You need to use in-text or parenthetical citations with paraphrasing.
Quotes, the exact words from a source, should be placed in quotation marks with the proper citation. Be careful not to have too many quotes or long passages of quotes.